• PHP stands for PHP: Hypertext Preprocessor
• PHP is a server-side scripting language, like ASP
• PHP scripts are executed on the server
• PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
• PHP is an open source software
• PHP is free to download and use
What is a PHP File?
• PHP files can contain text, HTML tags and scripts
• PHP files are returned to the browser as plain HTML
• PHP files have a file extension of ".php", ".php3", or ".phtml"
What is MySQL?
• MySQL is a database server
• MySQL is ideal for both small and large applications
• MySQL supports standard SQL
• MySQL compiles on a number of platforms
• MySQL is free to download and use
PHP + MySQL
• PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)
Why PHP?
• PHP runs on different platforms (Windows, Linux, Unix, etc.)
• PHP is compatible with almost all servers used today (Apache, IIS, etc.)
• PHP is FREE to download from the official PHP resource: www.php.net
• PHP is easy to learn and runs efficiently on the server side
Where to Start?
To get access to a web server with PHP support, you can:
• Install Apache (or IIS) on your own server, install PHP, and MySQL
• Or find a web hosting plan with PHP and MySQL support
What do you Need?
If your server supports PHP you don't need to do anything.
Just create some .php files in your web directory, and the server will parse them for you. Because it is free, most web hosts offer PHP support.
However, if your server does not support PHP, you must install PHP.
Here is a link to a good tutorial from PHP.net on how to install PHP5:http://www.php.net/manual/en/install.php
Download PHP
Download PHP for free here: http://www.php.net/downloads.php
Download MySQL Database
Download MySQL for free here: http://www.mysql.com/downloads/index.html
Download Apache Server
Download Apache for free here: http://httpd.apache.org/download.cgi
PHP code is executed on the server, and the plain HTML result is sent to the browser.
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Basic PHP Syntax
A PHP scripting block always starts with . A PHP scripting block can be placed anywhere in the document.
On servers with shorthand support enabled you can start a scripting block with .
For maximum compatibility, we recommend that you use the standard form (
A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.
Below, we have an example of a simple PHP script which sends the text "Hello World" to the browser:
Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.
There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text "Hello World".
Note: The file must have a .php extension. If the file has a .html extension, the PHP code will not be executed.
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Comments in PHP
In PHP, we use // to make a single-line comment or /* and */ to make a large comment block.
PHP Variables
A variable is used to store information.
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Variables in PHP
Variables are used for storing a values, like text strings, numbers or arrays.
When a variable is declared, it can be used over and over again in your script.
All variables in PHP start with a $ sign symbol.
The correct way of declaring a variable in PHP:
$var_name = value;
New PHP programmers often forget the $ sign at the beginning of the variable. In that case it will not work.
Let's try creating a variable containing a string, and a variable containing a number:
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PHP is a Loosely Typed Language
In PHP, a variable does not need to be declared before adding a value to it.
In the example above, you see that you do not have to tell PHP which data type the variable is.
PHP automatically converts the variable to the correct data type, depending on its value.
In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.
In PHP, the variable is declared automatically when you use it.
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Naming Rules for Variables
• A variable name must start with a letter or an underscore "_"
• A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )
• A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)
PHP String Variables
A string variable is used to store and manipulate text.
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String Variables in PHP
String variables are used for values that contains characters.
In this chapter we are going to look at the most common functions and operators used to manipulate strings in PHP.
After we create a string we can manipulate it. A string can be used directly in a function or it can be stored in a variable.
Below, the PHP script assigns the text "Hello World" to a string variable called $txt:
The output of the code above will be:
Hello World
Now, lets try to use some different functions and operators to manipulate the string.
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The Concatenation Operator
There is only one string operator in PHP.
The concatenation operator (.) is used to put two string values together.
To concatenate two string variables together, use the concatenation operator:
The output of the code above will be:
Hello World! What a nice day!
If we look at the code above you see that we used the concatenation operator two times. This is because we had to insert a third string (a space character), to separate the two strings.
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The strlen() function
The strlen() function is used to return the length of a string.
Let's find the length of a string:
The output of the code above will be:
12
The length of a string is often used in loops or other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the last character in the string).
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The strpos() function
The strpos() function is used to search for character within a string.
If a match is found, this function will return the position of the first match. If no match is found, it will return FALSE.
Let's see if we can find the string "world" in our string:
The output of the code above will be:
6
The position of the string "world" in our string is position 6. The reason that it is 6 (and not 7), is that the first position in the string is 0, and not 1.
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Complete PHP String Reference
For a complete reference of all string functions, go to our complete PHP String Reference.
The reference contains a brief description, and examples of use, for each function!
PHP Operators
Operators are used to operate on values.
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PHP Operators
This section lists the different operators used in PHP.
Arithmetic Operators
Operator Description Example Result
+ Addition x=2
x+2 4
- Subtraction x=2
5-x 3
* Multiplication x=4
x*5 20
/ Division 15/5
5/2 3
2.5
% Modulus (division remainder) 5%2
10%8
10%2 1
2
0
++ Increment x=5
x++ x=6
-- Decrement x=5
x-- x=4
Assignment Operators
Operator Example Is The Same As
= x=y x=y
+= x+=y x=x+y
-= x-=y x=x-y
*= x*=y x=x*y
/= x/=y x=x/y
.= x.=y x=x.y
%= x%=y x=x%y
Comparison Operators
Operator Description Example
== is equal to 5==8 returns false
!= is not equal 5!=8 returns true
<> is not equal 5<>8 returns true
> is greater than 5>8 returns false
< is less than 5<8 returns true >= is greater than or equal to 5>=8 returns false
<= is less than or equal to 5<=8 returns true Logical Operators Operator Description Example && and x=6 y=3 (x < 10 && y > 1) returns true
|| or x=6
y=3
(x==5 || y==5) returns false
! not x=6
y=3
!(x==y) returns true
PHP If...Else Statements
Conditional statements are used to perform different actions based on different conditions.
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Conditional Statements
Very often when you write code, you want to perform different actions for different decisions.
You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:
• if statement - use this statement to execute some code only if a specified condition is true
• if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false
• if...elseif....else statement - use this statement to select one of several blocks of code to be executed
• switch statement - use this statement to select one of many blocks of code to be executed
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The if Statement
Use the if statement to execute some code only if a specified condition is true.
Syntax
if (condition) code to be executed if condition is true;
The following example will output "Have a nice weekend!" if the current day is Friday:
Notice that there is no ..else.. in this syntax. The code is executed only if the specified condition is true.
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The if...else Statement
Use the if....else statement to execute some code if a condition is true and another code if a condition is false.
Syntax
if (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
Example
The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":
If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:
";
echo "Have a nice weekend!";
echo "See you on Monday!";
}
?>
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The if...elseif....else Statement
Use the if....elseif...else statement to select one of several blocks of code to be executed.
Syntax
if (condition)
code to be executed if condition is true;
elseif (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
Example
The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":
PHP Switch Statement
Conditional statements are used to perform different actions based on different conditions.
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The PHP Switch Statement
Use the switch statement to select one of many blocks of code to be executed.
Syntax
switch (n)
{
case label1:
code to be executed if n=label1;
break;
case label2:
code to be executed if n=label2;
break;
default:
code to be executed if n is different from both label1 and label2;
}
This is how it works: First we have a single expression n (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically. The default statement is used if no match is found.
Example
PHP Arrays
An array stores multiple values in one single variable.
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What is an Array?
A variable is a storage area holding a number or text. The problem is, a variable will hold only one value.
An array is a special variable, which can store multiple values in one single variable.
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:
$cars1="Saab";
$cars2="Volvo";
$cars3="BMW";
However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?
The best solution here is to use an array!
An array can hold all your variable values under a single name. And you can access the values by referring to the array name.
Each element in the array has its own index so that it can be easily accessed.
In PHP, there are three kind of arrays:
• Numeric array - An array with a numeric index
• Associative array - An array where each ID key is associated with a value
• Multidimensional array - An array containing one or more arrays
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Numeric Arrays
A numeric array stores each array element with a numeric index.
There are two methods to create a numeric array.
1. In the following example the index are automatically assigned (the index starts at 0):
$cars=array("Saab","Volvo","BMW","Toyota");
2. In the following example we assign the index manually:
$cars[0]="Saab";
$cars[1]="Volvo";
$cars[2]="BMW";
$cars[3]="Toyota";
Example
In the following example you access the variable values by referring to the array name and index:
The code above will output:
Saab and Volvo are Swedish cars.
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Associative Arrays
An associative array, each ID key is associated with a value.
When storing data about specific named values, a numerical array is not always the best way to do it.
With associative arrays we can use the values as keys and assign values to them.
Example 1
In this example we use an array to assign ages to the different persons:
$ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34);
Example 2
This example is the same as example 1, but shows a different way of creating the array:
$ages['Peter'] = "32";
$ages['Quagmire'] = "30";
$ages['Joe'] = "34";
The ID keys can be used in a script:
The code above will output:
Peter is 32 years old.
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Multidimensional Arrays
In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.
Example
In this example we create a multidimensional array, with automatically assigned ID keys:
$families = array
(
"Griffin"=>array
(
"Peter",
"Lois",
"Megan"
),
"Quagmire"=>array
(
"Glenn"
),
"Brown"=>array
(
"Cleveland",
"Loretta",
"Junior"
)
);
The array above would look like this if written to the output:
Array
(
[Griffin] => Array
(
[0] => Peter
[1] => Lois
[2] => Megan
)
[Quagmire] => Array
(
[0] => Glenn
)
[Brown] => Array
(
[0] => Cleveland
[1] => Loretta
[2] => Junior
)
)
Example 2
Lets try displaying a single value from the array above:
echo "Is " . $families['Griffin'][2] .
" a part of the Griffin family?";
The code above will output:
Is Megan a part of the Griffin family?
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Complete PHP Array Reference
For a complete reference of all array functions, go to our complete PHP Array Reference.
The reference contains a brief description, and examples of use, for each function!
PHP Looping - While Loops
Loops execute a block of code a specified number of times, or while a specified condition is true.
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PHP Loops
Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.
In PHP, we have the following looping statements:
• while - loops through a block of code while a specified condition is true
• do...while - loops through a block of code once, and then repeats the loop as long as a specified condition is true
• for - loops through a block of code a specified number of times
• foreach - loops through a block of code for each element in an array
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The while Loop
The while loop executes a block of code while a condition is true.
Syntax
while (condition)
{
code to be executed;
}
Example
The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:
";
$i++;
}
?>
Output:
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
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The do...while Statement
The do...while statement will always execute the block of code once, it will then check the condition, and repeat the loop while the condition is true.
Syntax
do
{
code to be executed;
}
while (condition);
Example
The example below defines a loop that starts with i=1. It will then increment i with 1, and write some output. Then the condition is checked, and the loop will continue to run as long as i is less than, or equal to 5:
";
}
while ($i<=5); ?>
Output:
The number is 2
The number is 3
The number is 4
The number is 5
The number is 6
The for loop and the foreach loop will be explained in the next chapter.
PHP Looping - For Loops
Loops execute a block of code a specified number of times, or while a specified condition is true.
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The for Loop
The for loop is used when you know in advance how many times the script should run.
Syntax
for (init; condition; increment)
{
code to be executed;
}
Parameters:
• init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop)
• condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
• increment: Mostly used to increment a counter (but can be any code to be executed at the end of the loop)
Note: Each of the parameters above can be empty, or have multiple expressions (separated by commas).
Example
The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:
";
}
?>
Output:
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
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The foreach Loop
The foreach loop is used to loop through arrays.
Syntax
foreach ($array as $value)
{
code to be executed;
}
For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value.
Example
The following example demonstrates a loop that will print the values of the given array:
";
}
?>
Output:
one
two
three
PHP Functions
The real power of PHP comes from its functions.
In PHP, there are more than 700 built-in functions.
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PHP Built-in Functions
For a complete reference and examples of the built-in functions, please visit our PHP Reference.
________________________________________
PHP Functions
In this chapter we will show you how to create your own functions.
To keep the script from being executed when the page loads, you can put it into a function.
A function will be executed by a call to the function.
You may call a function from anywhere within a page.
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Create a PHP Function
A function will be executed by a call to the function.
Syntax
function functionName()
{
code to be executed;
}
PHP function guidelines:
• Give the function a name that reflects what the function does
• The function name can start with a letter or underscore (not a number)
Example
A simple function that writes my name when it is called:
Output:
My name is Kai Jim Refsnes
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PHP Functions - Adding parameters
To add more functionality to a function, we can add parameters. A parameter is just like a variable.
Parameters are specified after the function name, inside the parentheses.
Example 1
The following example will write different first names, but equal last name:
";
}
echo "My name is ";
writeName("Kai Jim");
echo "My sister's name is ";
writeName("Hege");
echo "My brother's name is ";
writeName("Stale");
?>
Output:
My name is Kai Jim Refsnes.
My sister's name is Hege Refsnes.
My brother's name is Stale Refsnes.
Example 2
The following function has two parameters:
";
}
echo "My name is ";
writeName("Kai Jim",".");
echo "My sister's name is ";
writeName("Hege","!");
echo "My brother's name is ";
writeName("Ståle","?");
?>
Output:
My name is Kai Jim Refsnes.
My sister's name is Hege Refsnes!
My brother's name is Ståle Refsnes?
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PHP Functions - Return values
To let a function return a value, use the return statement.
Example
Output:
1 + 16 = 17
PHP Forms and User Input
The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
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PHP Form Handling
The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.
Example
The example below contains an HTML form with two input fields and a submit button:
When a user fills out the form above and click on the submit button, the form data is sent to a PHP file, called "welcome.php":
"welcome.php" looks like this:
Welcome !
You are years old.
Output could be something like this:
Welcome John!
You are 28 years old.
The PHP $_GET and $_POST functions will be explained in the next chapters.
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Form Validation
User input should be validated on the browser whenever possible (by client scripts). Browser validation is faster and reduces the server load.
You should consider server validation if the user input will be inserted into a database. A good way to validate a form on the server is to post the form to itself, instead of jumping to a different page. The user will then get the error messages on the same page as the form. This makes it easier to discover the error.
PHP $_GET Function
The built-in $_GET function is used to collect values in a form with method="get".
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The $_GET Function
The built-in $_GET function is used to collect values from a form sent with method="get".
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send (max. 100 characters).
Example
When the user clicks the "Submit" button, the URL sent to the server could look something like this:
http://www.w3schools.com/welcome.php?fname=Peter&age=37
The "welcome.php" file can now use the $_GET function to collect form data (the names of the form fields will automatically be the keys in the $_GET array):
Welcome .
You are years old!
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When to use method="get"?
When using method="get" in HTML forms, all variable names and values are displayed in the URL.
Note: This method should not be used when sending passwords or other sensitive information!
However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.
Note: The get method is not suitable for large variable values; the value cannot exceed 100 characters.
PHP $_POST Function
The built-in $_POST function is used to collect values in a form with method="post".
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The $_POST Function
The built-in $_POST function is used to collect values from a form sent with method="post".
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Note: However, there is an 8 Mb max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).
Example
When the user clicks the "Submit" button, the URL will look like this:
http://www.w3schools.com/welcome.php
The "welcome.php" file can now use the $_POST function to collect form data (the names of the form fields will automatically be the keys in the $_POST array):
Welcome !
You are years old.
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When to use method="post"?
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.
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The PHP $_REQUEST Function
The PHP built-in $_REQUEST function contains the contents of both $_GET, $_POST, and $_COOKIE.
The $_REQUEST function can be used to collect form data sent with both the GET and POST methods.
Example
Welcome !
You are years old.
PHP advanced
PHP Date() Function
The PHP date() function is used to format a time and/or date.
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The PHP Date() Function
The PHP date() function formats a timestamp to a more readable date and time.
A timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred.
Syntax
date(format,timestamp)
Parameter Description
format Required. Specifies the format of the timestamp
timestamp Optional. Specifies a timestamp. Default is the current date and time
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PHP Date() - Format the Date
The required format parameter in the date() function specifies how to format the date/time.
Here are some characters that can be used:
• d - Represents the day of the month (01 to 31)
• m - Represents a month (01 to 12)
• Y - Represents a year (in four digits)
A list of all the characters that can be used in the format parameter, can be found in our PHP Date reference.
Other characters, like"/", ".", or "-" can also be inserted between the letters to add additional formatting:
";
echo date("Y.m.d") . "
";
echo date("Y-m-d")
?>
The output of the code above could be something like this:
2009/05/11
2009.05.11
2009-05-11
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PHP Date() - Adding a Timestamp
The optional timestamp parameter in the date() function specifies a timestamp. If you do not specify a timestamp, the current date and time will be used.
The mktime() function returns the Unix timestamp for a date.
The Unix timestamp contains the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified.
Syntax for mktime()
mktime(hour,minute,second,month,day,year,is_dst)
To go one day in the future we simply add one to the day argument of mktime():
The output of the code above could be something like this:
Tomorrow is 2009/05/12
________________________________________
Complete PHP Date Reference
For a complete reference of all date functions, go to our complete PHP Date Reference.
The reference contains a brief description, and examples of use, for each function!
PHP Include File
Server Side Includes (SSI)
You can insert the content of one PHP file into another PHP file before the server executes it, with the include() or require() function.
The two functions are identical in every way, except how they handle errors:
• include() generates a warning, but the script will continue execution
• require() generates a fatal error, and the script will stop
These two functions are used to create functions, headers, footers, or elements that will be reused on multiple pages.
Server side includes saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. When the header needs to be updated, you can only update the include file, or when you add a new page to your site, you can simply change the menu file (instead of updating the links on all your web pages).
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PHP include() Function
The include() function takes all the content in a specified file and includes it in the current file.
If an error occurs, the include() function generates a warning, but the script will continue execution.
Example 1
Assume that you have a standard header file, called "header.php". To include the header file in a page, use the include() function:
Welcome to my home page!
Some text.
Example 2
Assume we have a standard menu file, called "menu.php", that should be used on all pages:
Home
Tutorials
References
Examples
About Us
Contact Us
All pages in the Web site should include this menu file. Here is how it can be done:
Welcome to my home page.
Some text.
If you look at the source code of the page above (in a browser), it will look like this:
Welcome to my home page!
Some text.
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PHP require() Function
The require() function is identical to include(), except that it handles errors differently.
If an error occurs, the include() function generates a warning, but the script will continue execution. The require() generates a fatal error, and the script will stop.
Error Example include() Function
Error message:
Warning: include(wrongFile.php) [function.include]:
failed to open stream:
No such file or directory in C:\home\website\test.php on line 5
Warning: include() [function.include]:
Failed opening 'wrongFile.php' for inclusion
(include_path='.;C:\php5\pear')
in C:\home\website\test.php on line 5
Hello World!
Notice that the echo statement is executed! This is because a Warning does not stop the script execution.
Error Example require() Function
Now, let's run the same example with the require() function.
Error message:
Warning: require(wrongFile.php) [function.require]:
failed to open stream:
No such file or directory in C:\home\website\test.php on line 5
Fatal error: require() [function.require]:
Failed opening required 'wrongFile.php'
(include_path='.;C:\php5\pear')
in C:\home\website\test.php on line 5
The echo statement is not executed, because the script execution stopped after the fatal error.
It is recommended to use the require() function instead of include(), because scripts should not continue after an error.
PHP File Handling
The fopen() function is used to open files in PHP.
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Opening a File
The fopen() function is used to open files in PHP.
The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:
The file may be opened in one of the following modes:
Modes Description
r Read only. Starts at the beginning of the file
r+ Read/Write. Starts at the beginning of the file
w Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist
w+ Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist
a Append. Opens and writes to the end of the file or creates a new file if it doesn't exist
a+ Read/Append. Preserves file content by writing to the end of the file
x Write only. Creates a new file. Returns FALSE and an error if file already exists
x+ Read/Write. Creates a new file. Returns FALSE and an error if file already exists
Note: If the fopen() function is unable to open the specified file, it returns 0 (false).
Example
The following example generates a message if the fopen() function is unable to open the specified file:
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Closing a File
The fclose() function is used to close an open file:
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Check End-of-file
The feof() function checks if the "end-of-file" (EOF) has been reached.
The feof() function is useful for looping through data of unknown length.
Note: You cannot read from files opened in w, a, and x mode!
if (feof($file)) echo "End of file";
________________________________________
Reading a File Line by Line
The fgets() function is used to read a single line from a file.
Note: After a call to this function the file pointer has moved to the next line.
Example
The example below reads a file line by line, until the end of file is reached:
";
}
fclose($file);
?>
________________________________________
Reading a File Character by Character
The fgetc() function is used to read a single character from a file.
Note: After a call to this function the file pointer moves to the next character.
Example
The example below reads a file character by character, until the end of file is reached:
________________________________________
PHP Filesystem Reference
For a full reference of the PHP filesystem functions, visit our PHP Filesystem Reference.
PHP File Upload
With PHP, it is possible to upload files to the server.
________________________________________
Create an Upload-File Form
To allow users to upload files from a form can be very useful.
Look at the following HTML form for uploading files:
Notice the following about the HTML form above:
• The enctype attribute of the
Retrieve the values in the "welcome.php" file like this:
Welcome .
You are years old.
PHP Sessions
A PHP session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are available to all pages in one application.
________________________________________
PHP Session Variables
When you are working with an application, you open it, do some changes and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are and what you do because the HTTP address doesn't maintain state.
A PHP session solves this problem by allowing you to store user information on the server for later use (i.e. username, shopping items, etc). However, session information is temporary and will be deleted after the user has left the website. If you need a permanent storage you may want to store the data in a database.
Sessions work by creating a unique id (UID) for each visitor and store variables based on this UID. The UID is either stored in a cookie or is propagated in the URL.
________________________________________
Starting a PHP Session
Before you can store user information in your PHP session, you must first start up the session.
Note: The session_start() function must appear BEFORE the tag:
The code above will register the user's session with the server, allow you to start saving user information, and assign a UID for that user's session.
________________________________________
Storing a Session Variable
The correct way to store and retrieve session variables is to use the PHP $_SESSION variable:
Output:
Pageviews=1
In the example below, we create a simple page-views counter. The isset() function checks if the "views" variable has already been set. If "views" has been set, we can increment our counter. If "views" doesn't exist, we create a "views" variable, and set it to 1:
________________________________________
Destroying a Session
If you wish to delete some session data, you can use the unset() or the session_destroy() function.
The unset() function is used to free the specified session variable:
You can also completely destroy the session by calling the session_destroy() function:
Note: session_destroy() will reset your session and you will lose all your stored session data.
PHP Sending E-mails
PHP allows you to send e-mails directly from a script.
________________________________________
The PHP mail() Function
The PHP mail() function is used to send emails from inside a script.
Syntax
mail(to,subject,message,headers,parameters)
Parameter Description
to Required. Specifies the receiver / receivers of the email
subject Required. Specifies the subject of the email. Note: This parameter cannot contain any newline characters
message Required. Defines the message to be sent. Each line should be separated with a LF (\n). Lines should not exceed 70 characters
headers Optional. Specifies additional headers, like From, Cc, and Bcc. The additional headers should be separated with a CRLF (\r\n)
parameters Optional. Specifies an additional parameter to the sendmail program
Note: For the mail functions to be available, PHP requires an installed and working email system. The program to be used is defined by the configuration settings in the php.ini file. Read more in our PHP Mail reference.
________________________________________
PHP Simple E-Mail
The simplest way to send an email with PHP is to send a text email.
In the example below we first declare the variables ($to, $subject, $message, $from, $headers), then we use the variables in the mail() function to send an e-mail:
________________________________________
PHP Mail Form
With PHP, you can create a feedback-form on your website. The example below sends a text message to a specified e-mail address:
Email:
Subject:
Message:
";
}
?>
This is how the example above works:
• First, check if the email input field is filled out
• If it is not set (like when the page is first visited); output the HTML form
• If it is set (after the form is filled out); send the email from the form
• When submit is pressed after the form is filled out, the page reloads, sees that the email input is set, and sends the email
Note: This is the simplest way to send e-mail, but it is not secure. In the next chapter of this tutorial you can read more about vulnerabilities in e-mail scripts, and how to validate user input to make it more secure.
________________________________________
PHP Mail Reference
For more information about the PHP mail() function, visit our PHP Mail Reference.
PHP Secure E-mails
________________________________________
There is a weakness in the PHP e-mail script in the previous chapter.
________________________________________
PHP E-mail Injections
First, look at the PHP code from the previous chapter:
Email:
Subject:
Message:
";
}
?>
The problem with the code above is that unauthorized users can insert data into the mail headers via the input form.
What happens if the user adds the following text to the email input field in the form?
someone@example.com%0ACc:person2@example.com
%0ABcc:person3@example.com,person3@example.com,
anotherperson4@example.com,person5@example.com
%0ABTo:person6@example.com
The mail() function puts the text above into the mail headers as usual, and now the header has an extra Cc:, Bcc:, and To: field. When the user clicks the submit button, the e-mail will be sent to all of the addresses above!
________________________________________
PHP Stopping E-mail Injections
The best way to stop e-mail injections is to validate the input.
The code below is the same as in the previous chapter, but now we have added an input validator that checks the email field in the form:
Email:
Subject:
Message:
";
}
?>
In the code above we use PHP filters to validate input:
• The FILTER_SANITIZE_EMAIL filter removes all illegal e-mail characters from a string
• The FILTER_VALIDATE_EMAIL filter validates value as an e-mail address
You can read more about filters in our PHP Filter chapter.
PHP Error Handling
The default error handling in PHP is very simple. An error message with filename, line number and a message describing the error is sent to the browser.
________________________________________
PHP Error Handling
When creating scripts and web applications, error handling is an important part. If your code lacks error checking code, your program may look very unprofessional and you may be open to security risks.
This tutorial contains some of the most common error checking methods in PHP.
We will show different error handling methods:
• Simple "die()" statements
• Custom errors and error triggers
• Error reporting
________________________________________
Basic Error Handling: Using the die() function
The first example shows a simple script that opens a text file:
If the file does not exist you might get an error like this:
Warning: fopen(welcome.txt) [function.fopen]: failed to open stream:
No such file or directory in C:\webfolder\test.php on line 2
To avoid that the user gets an error message like the one above, we test if the file exist before we try to access it:
Now if the file does not exist you get an error like this:
File not found
The code above is more efficient than the earlier code, because it uses a simple error handling mechanism to stop the script after the error.
However, simply stopping the script is not always the right way to go. Let's take a look at alternative PHP functions for handling errors.
________________________________________
Creating a Custom Error Handler
Creating a custom error handler is quite simple. We simply create a special function that can be called when an error occurs in PHP.
This function must be able to handle a minimum of two parameters (error level and error message) but can accept up to five parameters (optionally: file, line-number, and the error context):
Syntax
error_function(error_level,error_message,
error_file,error_line,error_context)
Parameter Description
error_level Required. Specifies the error report level for the user-defined error. Must be a value number. See table below for possible error report levels
error_message Required. Specifies the error message for the user-defined error
error_file Optional. Specifies the filename in which the error occurred
error_line Optional. Specifies the line number in which the error occurred
error_context Optional. Specifies an array containing every variable, and their values, in use when the error occurred
Error Report levels
These error report levels are the different types of error the user-defined error handler can be used for:
Value Constant Description
2 E_WARNING Non-fatal run-time errors. Execution of the script is not halted
8 E_NOTICE Run-time notices. The script found something that might be an error, but could also happen when running a script normally
256 E_USER_ERROR Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error()
512 E_USER_WARNING Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error()
1024 E_USER_NOTICE User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error()
4096 E_RECOVERABLE_ERROR Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler())
8191 E_ALL All errors and warnings, except level E_STRICT (E_STRICT will be part of E_ALL as of PHP 6.0)
Now lets create a function to handle errors:
function customError($errno, $errstr)
{
echo "Error: [$errno] $errstr
";
echo "Ending Script";
die();
}
The code above is a simple error handling function. When it is triggered, it gets the error level and an error message. It then outputs the error level and message and terminates the script.
Now that we have created an error handling function we need to decide when it should be triggered.
________________________________________
Set Error Handler
The default error handler for PHP is the built in error handler. We are going to make the function above the default error handler for the duration of the script.
It is possible to change the error handler to apply for only some errors, that way the script can handle different errors in different ways. However, in this example we are going to use our custom error handler for all errors:
set_error_handler("customError");
Since we want our custom function to handle all errors, the set_error_handler() only needed one parameter, a second parameter could be added to specify an error level.
Example
Testing the error handler by trying to output variable that does not exist:
Error: [$errno] $errstr";
}
//set error handler
set_error_handler("customError");
//trigger error
echo($test);
?>
The output of the code above should be something like this:
Error: [8] Undefined variable: test
________________________________________
Trigger an Error
In a script where users can input data it is useful to trigger errors when an illegal input occurs. In PHP, this is done by the trigger_error() function.
Example
In this example an error occurs if the "test" variable is bigger than "1":
1)
{
trigger_error("Value must be 1 or below");
}
?>
The output of the code above should be something like this:
Notice: Value must be 1 or below
in C:\webfolder\test.php on line 6
An error can be triggered anywhere you wish in a script, and by adding a second parameter, you can specify what error level is triggered.
Possible error types:
• E_USER_ERROR - Fatal user-generated run-time error. Errors that can not be recovered from. Execution of the script is halted
• E_USER_WARNING - Non-fatal user-generated run-time warning. Execution of the script is not halted
• E_USER_NOTICE - Default. User-generated run-time notice. The script found something that might be an error, but could also happen when running a script normally
Example
In this example an E_USER_WARNING occurs if the "test" variable is bigger than "1". If an E_USER_WARNING occurs we will use our custom error handler and end the script:
Error: [$errno] $errstr
";
echo "Ending Script";
die();
}
//set error handler
set_error_handler("customError",E_USER_WARNING);
//trigger error
$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or below",E_USER_WARNING);
}
?>
The output of the code above should be something like this:
Error: [512] Value must be 1 or below
Ending Script
Now that we have learned to create our own errors and how to trigger them, lets take a look at error logging.
________________________________________
Error Logging
By default, PHP sends an error log to the servers logging system or a file, depending on how the error_log configuration is set in the php.ini file. By using the error_log() function you can send error logs to a specified file or a remote destination.
Sending errors messages to yourself by e-mail can be a good way of getting notified of specific errors.
Send an Error Message by E-Mail
In the example below we will send an e-mail with an error message and end the script, if a specific error occurs:
Error: [$errno] $errstr
";
echo "Webmaster has been notified";
error_log("Error: [$errno] $errstr",1,
"someone@example.com","From: webmaster@example.com");
}
//set error handler
set_error_handler("customError",E_USER_WARNING);
//trigger error
$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or below",E_USER_WARNING);
}
?>
The output of the code above should be something like this:
Error: [512] Value must be 1 or below
Webmaster has been notified
And the mail received from the code above looks like this:
Error: [512] Value must be 1 or below
This should not be used with all errors. Regular errors should be logged on the server using the default PHP logging system.
PHP Exception Handling
Exceptions are used to change the normal flow of a script if a specified error occurs
________________________________________
What is an Exception
With PHP 5 came a new object oriented way of dealing with errors.
Exception handling is used to change the normal flow of the code execution if a specified error (exceptional) condition occurs. This condition is called an exception.
This is what normally happens when an exception is triggered:
• The current code state is saved
• The code execution will switch to a predefined (custom) exception handler function
• Depending on the situation, the handler may then resume the execution from the saved code state, terminate the script execution or continue the script from a different location in the code
We will show different error handling methods:
• Basic use of Exceptions
• Creating a custom exception handler
• Multiple exceptions
• Re-throwing an exception
• Setting a top level exception handler
Note: Exceptions should only be used with error conditions, and should not be used to jump to another place in the code at a specified point.
________________________________________
Basic Use of Exceptions
When an exception is thrown, the code following it will not be executed, and PHP will try to find the matching "catch" block.
If an exception is not caught, a fatal error will be issued with an "Uncaught Exception" message.
Lets try to throw an exception without catching it:
1)
{
throw new Exception("Value must be 1 or below");
}
return true;
}
//trigger exception
checkNum(2);
?>
The code above will get an error like this:
Fatal error: Uncaught exception 'Exception'
with message 'Value must be 1 or below' in C:\webfolder\test.php:6
Stack trace: #0 C:\webfolder\test.php(12):
checkNum(28) #1 {main} thrown in C:\webfolder\test.php on line 6
Try, throw and catch
To avoid the error from the example above, we need to create the proper code to handle an exception.
Proper exception code should include:
1. Try - A function using an exception should be in a "try" block. If the exception does not trigger, the code will continue as normal. However if the exception triggers, an exception is "thrown"
2. Throw - This is how you trigger an exception. Each "throw" must have at least one "catch"
3. Catch - A "catch" block retrieves an exception and creates an object containing the exception information
Lets try to trigger an exception with valid code:
1)
{
throw new Exception("Value must be 1 or below");
}
return true;
}
//trigger exception in a "try" block
try
{
checkNum(2);
//If the exception is thrown, this text will not be shown
echo 'If you see this, the number is 1 or below';
}
//catch exception
catch(Exception $e)
{
echo 'Message: ' .$e->getMessage();
}
?>
The code above will get an error like this:
Message: Value must be 1 or below
Example explained:
The code above throws an exception and catches it:
1. The checkNum() function is created. It checks if a number is greater than 1. If it is, an exception is thrown
2. The checkNum() function is called in a "try" block
3. The exception within the checkNum() function is thrown
4. The "catch" block retrives the exception and creates an object ($e) containing the exception information
5. The error message from the exception is echoed by calling $e->getMessage() from the exception object
However, one way to get around the "every throw must have a catch" rule is to set a top level exception handler to handle errors that slip through.
________________________________________
Creating a Custom Exception Class
Creating a custom exception handler is quite simple. We simply create a special class with functions that can be called when an exception occurs in PHP. The class must be an extension of the exception class.
The custom exception class inherits the properties from PHP's exception class and you can add custom functions to it.
Lets create an exception class:
getLine().' in '.$this->getFile()
.': '.$this->getMessage().' is not a valid E-Mail address';
return $errorMsg;
}
}
$email = "someone@example...com";
try
{
//check if
if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE)
{
//throw exception if email is not valid
throw new customException($email);
}
}
catch (customException $e)
{
//display custom message
echo $e->errorMessage();
}
?>
The new class is a copy of the old exception class with an addition of the errorMessage() function. Since it is a copy of the old class, and it inherits the properties and methods from the old class, we can use the exception class methods like getLine() and getFile() and getMessage().
Example explained:
The code above throws an exception and catches it with a custom exception class:
1. The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class
2. The errorMessage() function is created. This function returns an error message if an e-mail address is invalid
3. The $email variable is set to a string that is not a valid e-mail address
4. The "try" block is executed and an exception is thrown since the e-mail address is invalid
5. The "catch" block catches the exception and displays the error message
________________________________________
Multiple Exceptions
It is possible for a script to use multiple exceptions to check for multiple conditions.
It is possible to use several if..else blocks, a switch, or nest multiple exceptions. These exceptions can use different exception classes and return different error messages:
getLine().' in '.$this->getFile()
.': '.$this->getMessage().' is not a valid E-Mail address';
return $errorMsg;
}
}
$email = "someone@example.com";
try
{
//check if
if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE)
{
//throw exception if email is not valid
throw new customException($email);
}
//check for "example" in mail address
if(strpos($email, "example") !== FALSE)
{
throw new Exception("$email is an example e-mail");
}
}
catch (customException $e)
{
echo $e->errorMessage();
}
catch(Exception $e)
{
echo $e->getMessage();
}
?>
Example explained:
The code above tests two conditions and throws an exception if any of the conditions are not met:
1. The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class
2. The errorMessage() function is created. This function returns an error message if an e-mail address is invalid
3. The $email variable is set to a string that is a valid e-mail address, but contains the string "example"
4. The "try" block is executed and an exception is not thrown on the first condition
5. The second condition triggers an exception since the e-mail contains the string "example"
6. The "catch" block catches the exception and displays the correct error message
If there was no customException catch, only the base exception catch, the exception would be handled there
________________________________________
Re-throwing Exceptions
Sometimes, when an exception is thrown, you may wish to handle it differently than the standard way. It is possible to throw an exception a second time within a "catch" block.
A script should hide system errors from users. System errors may be important for the coder, but is of no interest to the user. To make things easier for the user you can re-throw the exception with a user friendly message:
getMessage().' is not a valid E-Mail address.';
return $errorMsg;
}
}
$email = "someone@example.com";
try
{
try
{
//check for "example" in mail address
if(strpos($email, "example") !== FALSE)
{
//throw exception if email is not valid
throw new Exception($email);
}
}
catch(Exception $e)
{
//re-throw exception
throw new customException($email);
}
}
catch (customException $e)
{
//display custom message
echo $e->errorMessage();
}
?>
Example explained:
The code above tests if the email-address contains the string "example" in it, if it does, the exception is re-thrown:
1. The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class
2. The errorMessage() function is created. This function returns an error message if an e-mail address is invalid
3. The $email variable is set to a string that is a valid e-mail address, but contains the string "example"
4. The "try" block contains another "try" block to make it possible to re-throw the exception
5. The exception is triggered since the e-mail contains the string "example"
6. The "catch" block catches the exception and re-throws a "customException"
7. The "customException" is caught and displays an error message
If the exception is not caught in its current "try" block, it will search for a catch block on "higher levels".
________________________________________
Set a Top Level Exception Handler
The set_exception_handler() function sets a user-defined function to handle all uncaught exceptions.
Exception: " , $exception->getMessage();
}
set_exception_handler('myException');
throw new Exception('Uncaught Exception occurred');
?>
The output of the code above should be something like this:
Exception: Uncaught Exception occurred
In the code above there was no "catch" block. Instead, the top level exception handler triggered. This function should be used to catch uncaught exceptions.
________________________________________
Rules for exceptions
• Code may be surrounded in a try block, to help catch potential exceptions
• Each try block or "throw" must have at least one corresponding catch block
• Multiple catch blocks can be used to catch different classes of exceptions
• Exceptions can be thrown (or re-thrown) in a catch block within a try block
A simple rule: If you throw something, you have to catch it.
PHP Filter
PHP filters are used to validate and filter data coming from insecure sources, like user input.
________________________________________
What is a PHP Filter?
A PHP filter is used to validate and filter data coming from insecure sources.
To test, validate and filter user input or custom data is an important part of any web application.
The PHP filter extension is designed to make data filtering easier and quicker.
________________________________________
Why use a Filter?
Almost all web applications depend on external input. Usually this comes from a user or another application (like a web service). By using filters you can be sure your application gets the correct input type.
You should always filter all external data!
Input filtering is one of the most important application security issues.
What is external data?
• Input data from a form
• Cookies
• Web services data
• Server variables
• Database query results
________________________________________
Functions and Filters
To filter a variable, use one of the following filter functions:
• filter_var() - Filters a single variable with a specified filter
• filter_var_array() - Filter several variables with the same or different filters
• filter_input - Get one input variable and filter it
• filter_input_array - Get several input variables and filter them with the same or different filters
In the example below, we validate an integer using the filter_var() function:
The code above uses the "FILTER_VALIDATE_INT" filter to filter the variable. Since the integer is valid, the output of the code above will be: "Integer is valid".
If we try with a variable that is not an integer (like "123abc"), the output will be: "Integer is not valid".
For a complete list of functions and filters, visit our PHP Filter Reference.
________________________________________
Validating and Sanitizing
There are two kinds of filters:
Validating filters:
• Are used to validate user input
• Strict format rules (like URL or E-Mail validating)
• Returns the expected type on success or FALSE on failure
Sanitizing filters:
• Are used to allow or disallow specified characters in a string
• No data format rules
• Always return the string
________________________________________
Options and Flags
Options and flags are used to add additional filtering options to the specified filters.
Different filters have different options and flags.
In the example below, we validate an integer using the filter_var() and the "min_range" and "max_range" options:
array
(
"min_range"=>0,
"max_range"=>256
)
);
if(!filter_var($var, FILTER_VALIDATE_INT, $int_options))
{
echo("Integer is not valid");
}
else
{
echo("Integer is valid");
}
?>
Like the code above, options must be put in an associative array with the name "options". If a flag is used it does not need to be in an array.
Since the integer is "300" it is not in the specified range, and the output of the code above will be: "Integer is not valid".
For a complete list of functions and filters, visit our PHP Filter Reference. Check each filter to see what options and flags are available.
________________________________________
Validate Input
Let's try validating input from a form.
The first thing we need to do is to confirm that the input data we are looking for exists.
Then we filter the input data using the filter_input() function.
In the example below, the input variable "email" is sent to the PHP page:
Example Explained
The example above has an input (email) sent to it using the "GET" method:
1. Check if an "email" input variable of the "GET" type exist
2. If the input variable exists, check if it is a valid e-mail address
________________________________________
Sanitize Input
Let's try cleaning up an URL sent from a form.
First we confirm that the input data we are looking for exists.
Then we sanitize the input data using the filter_input() function.
In the example below, the input variable "url" is sent to the PHP page:
Example Explained
The example above has an input (url) sent to it using the "POST" method:
1. Check if the "url" input of the "POST" type exists
2. If the input variable exists, sanitize (take away invalid characters) and store it in the $url variable
If the input variable is a string like this "http://www.W3ååSchøøools.com/", the $url variable after the sanitizing will look like this:
http://www.W3Schools.com/
________________________________________
Filter Multiple Inputs
A form almost always consist of more than one input field. To avoid calling the filter_var or filter_input functions over and over, we can use the filter_var_array or the filter_input_array functions.
In this example we use the filter_input_array() function to filter three GET variables. The received GET variables is a name, an age and an e-mail address:
array
(
"filter"=>FILTER_SANITIZE_STRING
),
"age" => array
(
"filter"=>FILTER_VALIDATE_INT,
"options"=>array
(
"min_range"=>1,
"max_range"=>120
)
),
"email"=> FILTER_VALIDATE_EMAIL,
);
$result = filter_input_array(INPUT_GET, $filters);
if (!$result["age"])
{
echo("Age must be a number between 1 and 120.
");
}
elseif(!$result["email"])
{
echo("E-Mail is not valid.
");
}
else
{
echo("User input is valid");
}
?>
Example Explained
The example above has three inputs (name, age and email) sent to it using the "GET" method:
1. Set an array containing the name of input variables and the filters used on the specified input variables
2. Call the filter_input_array() function with the GET input variables and the array we just set
3. Check the "age" and "email" variables in the $result variable for invalid inputs. (If any of the input variables are invalid, that input variable will be FALSE after the filter_input_array() function)
The second parameter of the filter_input_array() function can be an array or a single filter ID.
If the parameter is a single filter ID all values in the input array are filtered by the specified filter.
If the parameter is an array it must follow these rules:
• Must be an associative array containing an input variable as an array key (like the "age" input variable)
• The array value must be a filter ID or an array specifying the filter, flags and options
________________________________________
Using Filter Callback
It is possible to call a user defined function and use it as a filter using the FILTER_CALLBACK filter. This way, we have full control of the data filtering.
You can create your own user defined function or use an existing PHP function
The function you wish to use to filter is specified the same way as an option is specified. In an associative array with the name "options"
In the example below, we use a user created function to convert all "_" to whitespaces:
"convertSpace"));
?>
The result from the code above should look like this:
Peter is a great guy!
Example Explained
The example above converts all "_" to whitespaces:
1. Create a function to replace "_" to whitespaces
2. Call the filter_var() function with the FILTER_CALLBACK filter and an array containing our function
PHP Database
PHP MySQL Introduction
MySQL is the most popular open-source database system.
________________________________________
What is MySQL?
MySQL is a database.
The data in MySQL is stored in database objects called tables.
A table is a collections of related data entries and it consists of columns and rows.
Databases are useful when storing information categorically. A company may have a database with the following tables: "Employees", "Products", "Customers" and "Orders".
________________________________________
Database Tables
A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.
Below is an example of a table called "Persons":
LastName FirstName Address City
Hansen Ola Timoteivn 10 Sandnes
Svendson Tove Borgvn 23 Sandnes
Pettersen Kari Storgt 20 Stavanger
The table above contains three records (one for each person) and four columns (LastName, FirstName, Address, and City).
________________________________________
Queries
A query is a question or a request.
With MySQL, we can query a database for specific information and have a recordset returned.
Look at the following query:
SELECT LastName FROM Persons
The query above selects all the data in the "LastName" column from the "Persons" table, and will return a recordset like this:
LastName
Hansen
Svendson
Pettersen
________________________________________
Download MySQL Database
If you don't have a PHP server with a MySQL Database, you can download MySQL for free here:http://www.mysql.com/downloads/index.html
________________________________________
Facts About MySQL Database
One great thing about MySQL is that it can be scaled down to support embedded database applications. Perhaps it is because of this reputation that many people believe that MySQL can only handle small to medium-sized systems.
The truth is that MySQL is the de-facto standard database for web sites that support huge volumes of both data and end users (like Friendster, Yahoo, Google).
Look at http://www.mysql.com/customers/ for an overview of companies using MySQL.
PHP MySQL Connect to a Database
The free MySQL database is very often used with PHP.
________________________________________
Create a Connection to a MySQL Database
Before you can access data in a database, you must create a connection to the database.
In PHP, this is done with the mysql_connect() function.
Syntax
mysql_connect(servername,username,password);
Parameter Description
servername Optional. Specifies the server to connect to. Default value is "localhost:3306"
username Optional. Specifies the username to log in with. Default value is the name of the user that owns the server process
password Optional. Specifies the password to log in with. Default is ""
Note: There are more available parameters, but the ones listed above are the most important. Visit our full PHP MySQL Reference for more details.
Example
In the following example we store the connection in a variable ($con) for later use in the script. The "die" part will be executed if the connection fails:
________________________________________
Closing a Connection
The connection will be closed automatically when the script ends. To close the connection before, use the mysql_close() function:
PHP MySQL Create Database and Tables
A database holds one or multiple tables.
________________________________________
Create a Database
The CREATE DATABASE statement is used to create a database in MySQL.
Syntax
CREATE DATABASE database_name
To learn more about SQL, please visit our SQL tutorial.
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
Example
The following example creates a database called "my_db":
________________________________________
Create a Table
The CREATE TABLE statement is used to create a table in MySQL.
Syntax
CREATE TABLE table_name
(
column_name1 data_type,
column_name2 data_type,
column_name3 data_type,
....
)
To learn more about SQL, please visit our SQL tutorial.
We must add the CREATE TABLE statement to the mysql_query() function to execute the command.
Example
The following example creates a table named "Persons", with three columns. The column names will be "FirstName", "LastName" and "Age":
Important: A database must be selected before a table can be created. The database is selected with the mysql_select_db() function.
Note: When you create a database field of type varchar, you must specify the maximum length of the field, e.g. varchar(15).
The data type specifies what type of data the column can hold. For a complete reference of all the data types available in MySQL, go to our complete Data Types reference.
________________________________________
Primary Keys and Auto Increment Fields
Each table should have a primary key field.
A primary key is used to uniquely identify the rows in a table. Each primary key value must be unique within the table. Furthermore, the primary key field cannot be null because the database engine requires a value to locate the record.
The following example sets the personID field as the primary key field. The primary key field is often an ID number, and is often used with the AUTO_INCREMENT setting. AUTO_INCREMENT automatically increases the value of the field by 1 each time a new record is added. To ensure that the primary key field cannot be null, we must add the NOT NULL setting to the field.
Example
$sql = "CREATE TABLE Persons
(
personID int NOT NULL AUTO_INCREMENT,
PRIMARY KEY(personID),
FirstName varchar(15),
LastName varchar(15),
Age int
)";
mysql_query($sql,$con);
PHP MySQL Insert Into
The INSERT INTO statement is used to insert new records in a table.
________________________________________
Insert Data Into a Database Table
The INSERT INTO statement is used to add new records to a database table.
Syntax
It is possible to write the INSERT INTO statement in two forms.
The first form doesn't specify the column names where the data will be inserted, only their values:
INSERT INTO table_name
VALUES (value1, value2, value3,...)
The second form specifies both the column names and the values to be inserted:
INSERT INTO table_name (column1, column2, column3,...)
VALUES (value1, value2, value3,...)
To learn more about SQL, please visit our SQL tutorial.
To get PHP to execute the statements above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
Example
In the previous chapter we created a table named "Persons", with three columns; "Firstname", "Lastname" and "Age". We will use the same table in this example. The following example adds two new records to the "Persons" table:
________________________________________
Insert Data From a Form Into a Database
Now we will create an HTML form that can be used to add new records to the "Persons" table.
Here is the HTML form:
When a user clicks the submit button in the HTML form in the example above, the form data is sent to "insert.php".
The "insert.php" file connects to a database, and retrieves the values from the form with the PHP $_POST variables.
Then, the mysql_query() function executes the INSERT INTO statement, and a new record will be added to the "Persons" table.
Here is the "insert.php" page:
PHP MySQL Select
The SELECT statement is used to select data from a database.
________________________________________
Select Data From a Database Table
The SELECT statement is used to select data from a database.
Syntax
SELECT column_name(s)
FROM table_name
To learn more about SQL, please visit our SQL tutorial.
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
Example
The following example selects all the data stored in the "Persons" table (The * character selects all the data in the table):
";
}
mysql_close($con);
?>
The example above stores the data returned by the mysql_query() function in the $result variable.
Next, we use the mysql_fetch_array() function to return the first row from the recordset as an array. Each call to mysql_fetch_array() returns the next row in the recordset. The while loop loops through all the records in the recordset. To print the value of each row, we use the PHP $row variable ($row['FirstName'] and $row['LastName']).
The output of the code above will be:
Peter Griffin
Glenn Quagmire
________________________________________
Display the Result in an HTML Table
The following example selects the same data as the example above, but will display the data in an HTML table:
while($row = mysql_fetch_array($result))
{
echo "
echo "
echo "
echo "
}
echo "";
mysql_close($con);
?>
The output of the code above will be:
Firstname Lastname
Glenn Quagmire
Peter Griffin
PHP MySQL The Where Clause
The WHERE clause is used to filter records.
________________________________________
The WHERE clause
The WHERE clause is used to extract only those records that fulfill a specified criterion.
Syntax
SELECT column_name(s)
FROM table_name
WHERE column_name operator value
To learn more about SQL, please visit our SQL tutorial.
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
Example
The following example selects all rows from the "Persons" table where "FirstName='Peter':
";
}
?>
The output of the code above will be:
Peter Griffin
PHP MySQL Order By Keyword
The ORDER BY keyword is used to sort the data in a recordset.
________________________________________
The ORDER BY Keyword
The ORDER BY keyword is used to sort the data in a recordset.
The ORDER BY keyword sort the records in ascending order by default.
If you want to sort the records in a descending order, you can use the DESC keyword.
Syntax
SELECT column_name(s)
FROM table_name
ORDER BY column_name(s) ASC|DESC
To learn more about SQL, please visit our SQL tutorial.
Example
The following example selects all the data stored in the "Persons" table, and sorts the result by the "Age" column:
";
}
mysql_close($con);
?>
The output of the code above will be:
Glenn Quagmire 33
Peter Griffin 35
________________________________________
Order by Two Columns
It is also possible to order by more than one column. When ordering by more than one column, the second column is only used if the values in the first column are equal:
SELECT column_name(s)
FROM table_name
ORDER BY column1, column2
PHP MySQL Update
The UPDATE statement is used to modify data in a table.
________________________________________
Update Data In a Database
The UPDATE statement is used to update existing records in a table.
Syntax
UPDATE table_name
SET column1=value, column2=value2,...
WHERE some_column=some_value
Note: Notice the WHERE clause in the UPDATE syntax. The WHERE clause specifies which record or records that should be updated. If you omit the WHERE clause, all records will be updated!
To learn more about SQL, please visit our SQL tutorial.
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
Example
Earlier in the tutorial we created a table named "Persons". Here is how it looks:
FirstName LastName Age
Peter Griffin 35
Glenn Quagmire 33
The following example updates some data in the "Persons" table:
After the update, the "Persons" table will look like this:
FirstName LastName Age
Peter Griffin 36
Glenn Quagmire 33
PHP MySQL Delete
The DELETE statement is used to delete records in a table.
________________________________________
Delete Data In a Database
The DELETE FROM statement is used to delete records from a database table.
Syntax
DELETE FROM table_name
WHERE some_column = some_value
Note: Notice the WHERE clause in the DELETE syntax. The WHERE clause specifies which record or records that should be deleted. If you omit the WHERE clause, all records will be deleted!
To learn more about SQL, please visit our SQL tutorial.
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
Example
Look at the following "Persons" table:
FirstName LastName Age
Peter Griffin 35
Glenn Quagmire 33
The following example deletes all the records in the "Persons" table where LastName='Griffin':
After the deletion, the table will look like this:
FirstName LastName Age
Glenn Quagmire 33
PHP Database ODBC
ODBC is an Application Programming Interface (API) that allows you to connect to a data source (e.g. an MS Access database).
________________________________________
Create an ODBC Connection
With an ODBC connection, you can connect to any database, on any computer in your network, as long as an ODBC connection is available.
Here is how to create an ODBC connection to a MS Access Database:
1. Open the Administrative Tools icon in your Control Panel.
2. Double-click on the Data Sources (ODBC) icon inside.
3. Choose the System DSN tab.
4. Click on Add in the System DSN tab.
5. Select the Microsoft Access Driver. Click Finish.
6. In the next screen, click Select to locate the database.
7. Give the database a Data Source Name (DSN).
8. Click OK.
Note that this configuration has to be done on the computer where your web site is located. If you are running Internet Information Server (IIS) on your own computer, the instructions above will work, but if your web site is located on a remote server, you have to have physical access to that server, or ask your web host to to set up a DSN for you to use.
________________________________________
Connecting to an ODBC
The odbc_connect() function is used to connect to an ODBC data source. The function takes four parameters: the data source name, username, password, and an optional cursor type.
The odbc_exec() function is used to execute an SQL statement.
Example
The following example creates a connection to a DSN called northwind, with no username and no password. It then creates an SQL and executes it:
$conn=odbc_connect('northwind','','');
$sql="SELECT * FROM customers";
$rs=odbc_exec($conn,$sql);
________________________________________
Retrieving Records
The odbc_fetch_row() function is used to return records from the result-set. This function returns true if it is able to return rows, otherwise false.
The function takes two parameters: the ODBC result identifier and an optional row number:
odbc_fetch_row($rs)
________________________________________
Retrieving Fields from a Record
The odbc_result() function is used to read fields from a record. This function takes two parameters: the ODBC result identifier and a field number or name.
The code line below returns the value of the first field from the record:
$compname=odbc_result($rs,1);
The code line below returns the value of a field called "CompanyName":
$compname=odbc_result($rs,"CompanyName");
________________________________________
Closing an ODBC Connection
The odbc_close() function is used to close an ODBC connection.
odbc_close($conn);
________________________________________
An ODBC Example
The following example shows how to first create a database connection, then a result-set, and then display the data in an HTML table.
echo "
echo "
while (odbc_fetch_row($rs))
{
$compname=odbc_result($rs,"CompanyName");
$conname=odbc_result($rs,"ContactName");
echo "
echo "
}
odbc_close($conn);
echo "";
?>
PHP XML
PHP XML Expat Parser
The built-in Expat parser makes it possible to process XML documents in PHP.
________________________________________
What is XML?
XML is used to describe data and to focus on what data is. An XML file describes the structure of the data.
In XML, no tags are predefined. You must define your own tags.
If you want to learn more about XML, please visit our XML tutorial.
________________________________________
What is Expat?
To read and update - create and manipulate - an XML document, you will need an XML parser.
There are two basic types of XML parsers:
• Tree-based parser: This parser transforms an XML document into a tree structure. It analyzes the whole document, and provides access to the tree elements. e.g. the Document Object Model (DOM)
• Event-based parser: Views an XML document as a series of events. When a specific event occurs, it calls a function to handle it
The Expat parser is an event-based parser.
Event-based parsers focus on the content of the XML documents, not their structure. Because of this, event-based parsers can access data faster than tree-based parsers.
Look at the following XML fraction:
An event-based parser reports the XML above as a series of three events:
• Start element: from
• Start CDATA section, value: Jani
• Close element: from
The XML example above contains well-formed XML. However, the example is not valid XML, because there is no Document Type Definition (DTD) associated with it.
However, this makes no difference when using the Expat parser. Expat is a non-validating parser, and ignores any DTDs.
As an event-based, non-validating XML parser, Expat is fast and small, and a perfect match for PHP web applications.
Note: XML documents must be well-formed or Expat will generate an error.
________________________________________
Installation
The XML Expat parser functions are part of the PHP core. There is no installation needed to use these functions.
________________________________________
An XML File
The XML file below will be used in our example:
Don't forget me this weekend!
________________________________________
Initializing the XML Parser
We want to initialize the XML parser in PHP, define some handlers for different XML events, and then parse the XML file.
Example
";
break;
case "TO":
echo "To: ";
break;
case "FROM":
echo "From: ";
break;
case "HEADING":
echo "Heading: ";
break;
case "BODY":
echo "Message: ";
}
}
//Function to use at the end of an element
function stop($parser,$element_name)
{
echo "
";
}
//Function to use when finding character data
function char($parser,$data)
{
echo $data;
}
//Specify element handler
xml_set_element_handler($parser,"start","stop");
//Specify data handler
xml_set_character_data_handler($parser,"char");
//Open XML file
$fp=fopen("test.xml","r");
//Read data
while ($data=fread($fp,4096))
{
xml_parse($parser,$data,feof($fp)) or
die (sprintf("XML Error: %s at line %d",
xml_error_string(xml_get_error_code($parser)),
xml_get_current_line_number($parser)));
}
//Free the XML parser
xml_parser_free($parser);
?>
The output of the code above will be:
-- Note --
To: Tove
From: Jani
Heading: Reminder
Message: Don't forget me this weekend!
How it works:
1. Initialize the XML parser with the xml_parser_create() function
2. Create functions to use with the different event handlers
3. Add the xml_set_element_handler() function to specify which function will be executed when the parser encounters the opening and closing tags
4. Add the xml_set_character_data_handler() function to specify which function will execute when the parser encounters character data
5. Parse the file "test.xml" with the xml_parse() function
6. In case of an error, add xml_error_string() function to convert an XML error to a textual description
7. Call the xml_parser_free() function to release the memory allocated with the xml_parser_create() function
________________________________________
More PHP Expat Parser
For more information about the PHP Expat functions, visit our PHP XML Parser Reference.
PHP XML DOM
The built-in DOM parser makes it possible to process XML documents in PHP.
________________________________________
What is DOM?
The W3C DOM provides a standard set of objects for HTML and XML documents, and a standard interface for accessing and manipulating them.
The W3C DOM is separated into different parts (Core, XML, and HTML) and different levels (DOM Level 1/2/3):
* Core DOM - defines a standard set of objects for any structured document
* XML DOM - defines a standard set of objects for XML documents
* HTML DOM - defines a standard set of objects for HTML documents
If you want to learn more about the XML DOM, please visit our XML DOM tutorial.
________________________________________
XML Parsing
To read and update - create and manipulate - an XML document, you will need an XML parser.
There are two basic types of XML parsers:
• Tree-based parser: This parser transforms an XML document into a tree structure. It analyzes the whole document, and provides access to the tree elements
• Event-based parser: Views an XML document as a series of events. When a specific event occurs, it calls a function to handle it
The DOM parser is an tree-based parser.
Look at the following XML document fraction:
The XML DOM sees the XML above as a tree structure:
• Level 1: XML Document
• Level 2: Root element:
• Level 3: Text element: "Jani"
________________________________________
Installation
The DOM XML parser functions are part of the PHP core. There is no installation needed to use these functions.
________________________________________
An XML File
The XML file below will be used in our example:
Don't forget me this weekend!
________________________________________
Load and Output XML
We want to initialize the XML parser, load the xml, and output it:
Example
load("note.xml");
print $xmlDoc->saveXML();
?>
The output of the code above will be:
Tove Jani Reminder Don't forget me this weekend!
If you select "View source" in the browser window, you will see the following HTML:
Don't forget me this weekend!
The example above creates a DOMDocument-Object and loads the XML from "note.xml" into it.
Then the saveXML() function puts the internal XML document into a string, so we can output it.
________________________________________
Looping through XML
We want to initialize the XML parser, load the XML, and loop through all elements of the
Example
load("note.xml");
$x = $xmlDoc->documentElement;
foreach ($x->childNodes AS $item)
{
print $item->nodeName . " = " . $item->nodeValue . "
";
}
?>
The output of the code above will be:
#text =
to = Tove
#text =
from = Jani
#text =
heading = Reminder
#text =
body = Don't forget me this weekend!
#text =
In the example above you see that there are empty text nodes between each element.
When XML generates, it often contains white-spaces between the nodes. The XML DOM parser treats these as ordinary elements, and if you are not aware of them, they sometimes cause problems.
________________________________________
If you want to learn more about the XML DOM, please visit our XML DOM tutorial.
PHP SimpleXML
SimpleXML handles the most common XML tasks and leaves the rest for other extensions.
________________________________________
What is SimpleXML?
SimpleXML is new in PHP 5. It is an easy way of getting an element's attributes and text, if you know the XML document's layout.
Compared to DOM or the Expat parser, SimpleXML just takes a few lines of code to read text data from an element.
SimpleXML converts the XML document into an object, like this:
• Elements - Are converted to single attributes of the SimpleXMLElement object. When there's more than one element on one level, they're placed inside an array
• Attributes - Are accessed using associative arrays, where an index corresponds to the attribute name
• Element Data - Text data from elements are converted to strings. If an element has more than one text node, they will be arranged in the order they are found
SimpleXML is fast and easy to use when performing basic tasks like:
• Reading XML files
• Extracting data from XML strings
• Editing text nodes or attributes
However, when dealing with advanced XML, like namespaces, you are better off using the Expat parser or the XML DOM.
________________________________________
Installation
As of PHP 5.0, the SimpleXML functions are part of the PHP core. There is no installation needed to use these functions.
________________________________________
Using SimpleXML
Below is an XML file:
Don't forget me this weekend!
We want to output the element names and data from the XML file above.
Here's what to do:
1. Load the XML file
2. Get the name of the first element
3. Create a loop that will trigger on each child node, using the children() function
4. Output the element name and data for each child node
Example
getName() . "
";
foreach($xml->children() as $child)
{
echo $child->getName() . ": " . $child . "
";
}
?>
The output of the code above will be:
note
to: Tove
from: Jani
heading: Reminder
body: Don't forget me this weekend!
________________________________________
More PHP SimpleXML
For more information about the PHP SimpleXML functions, visit our PHP SimpleXML Reference.
PHP and AJAX
AJAX Introduction
AJAX is about updating parts of a web page, without reloading the whole page.
________________________________________
What is AJAX?
AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.
AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.
________________________________________
How AJAX Works
________________________________________
AJAX is Based on Internet Standards
AJAX is based on internet standards, and uses a combination of:
• XMLHttpRequest object (to exchange data asynchronously with a server)
• JavaScript/DOM (to display/interact with the information)
• CSS (to style the data)
• XML (often used as the format for transferring data)
AJAX applications are browser- and platform-independent!
________________________________________
Google Suggest
AJAX was made popular in 2005 by Google, with Google Suggest.
Google Suggest is using AJAX to create a very dynamic web interface: When you start typing in Google's search box, a JavaScript sends the letters off to a server and the server returns a list of suggestions.
________________________________________
Start Using AJAX Today
In our PHP tutorial, we will demonstrate how AJAX can update parts of a web page, without reloading the whole page. The server script will be written in PHP.
If you want to learn more about AJAX, visit our AJAX tutorial.
PHP - AJAX and PHP
AJAX is used to create more interactive applications.
________________________________________
AJAX PHP Example
The following example will demonstrate how a web page can communicate with a web server while a user type characters in an input field:
Example
Start typing a name in the input field below:
First name:
Suggestions:
________________________________________
Example Explained - The HTML Page
When a user types a character in the input field above, the function "showHint()" is executed. The function is triggered by the "onkeyup" event:
Start typing a name in the input field below:
Suggestions:
Source code explanation:
If the input field is empty (str.length==0), the function clears the content of the txtHint placeholder and exits the function.
If the input field is not empty, the showHint() function executes the following:
• Create an XMLHttpRequest object
• Create the function to be executed when the server response is ready
• Send the request off to a file on the server
• Notice that a parameter (q) is added to the URL (with the content of the input field)
________________________________________
The PHP File
The page on the server called by the JavaScript above is a PHP file called "gethint.php".
The source code in "gethint.php" checks an array of names, and returns the corresponding name(s) to the browser:
0
if (strlen($q) > 0)
{
$hint="";
for($i=0; $i
Explanation: If there is any text sent from the JavaScript (strlen($q) > 0), the following happens:
1. Find a name matching the characters sent from the JavaScript
2. If no match were found, set the response string to "no suggestion"
3. If one or more matching names were found, set the response string to all these names
4. The response is sent to the "txtHint" placeholder
PHP - AJAX and MySQL
AJAX can be used for interactive communication with a database.
________________________________________
AJAX Database Example
The following example will demonstrate how a web page can fetch information from a database with AJAX:
Example
Person info will be listed here...
________________________________________
Example Explained - The MySQL Database
The database table we use in the example above looks like this:
id FirstName LastName Age Hometown Job
1 Peter Griffin 41 Quahog Brewery
2 Lois Griffin 40 Newport Piano Teacher
3 Joseph Swanson 39 Quahog Police Officer
4 Glenn Quagmire 41 Quahog Pilot
________________________________________
Example Explained - The HTML Page
When a user selects a user in the dropdown list above, a function called "showUser()" is executed. The function is triggered by the "onchange" event:
Person info will be listed here.
The showUser() function does the following:
• Check if a person is selected
• Create an XMLHttpRequest object
• Create the function to be executed when the server response is ready
• Send the request off to a file on the server
• Notice that a parameter (q) is added to the URL (with the content of the dropdown list)
________________________________________
The PHP File
The page on the server called by the JavaScript above is a PHP file called "getuser.php".
The source code in "getuser.php" runs a query against a MySQL database, and returns the result in an HTML table:
while($row = mysql_fetch_array($result))
{
echo "
echo "
echo "
echo "
echo "
echo "
echo "
}
echo "";
mysql_close($con);
?>
Explanation: When the query is sent from the JavaScript to the PHP file, the following happens:
1. PHP opens a connection to a MySQL server
2. The correct person is found
3. An HTML table is created, filled with data, and sent back to the "txtHint" placeholder
PHP Example - AJAX and XML
AJAX can be used for interactive communication with an XML file.
________________________________________
AJAX XML Example
The following example will demonstrate how a web page can fetch information from an XML file with AJAX:
Example
CD info will be listed here...
________________________________________
Example Explained - The HTML Page
When a user selects a CD in the dropdown list above, a function called "showCD()" is executed. The function is triggered by the "onchange" event:
CD info will be listed here...
The showCD() function does the following:
• Check if a CD is selected
• Create an XMLHttpRequest object
• Create the function to be executed when the server response is ready
• Send the request off to a file on the server
• Notice that a parameter (q) is added to the URL (with the content of the dropdown list)
________________________________________
The PHP File
The page on the server called by the JavaScript above is a PHP file called "getcd.php".
The PHP script loads an XML document, "cd_catalog.xml", runs a query against the XML file, and returns the result as HTML:
load("cd_catalog.xml");
$x=$xmlDoc->getElementsByTagName('ARTIST');
for ($i=0; $i<=$x->length-1; $i++)
{
//Process only element nodes
if ($x->item($i)->nodeType==1)
{
if ($x->item($i)->childNodes->item(0)->nodeValue == $q)
{
$y=($x->item($i)->parentNode);
}
}
}
$cd=($y->childNodes);
for ($i=0;$i<$cd->length;$i++)
{
//Process only element nodes
if ($cd->item($i)->nodeType==1)
{
echo("" . $cd->item($i)->nodeName . ": ");
echo($cd->item($i)->childNodes->item(0)->nodeValue);
echo("
");
}
}
?>
When the CD query is sent from the JavaScript to the PHP page, the following happens:
1. PHP creates an XML DOM object
2. Find all
3. Output the album information (send to the "txtHint" placeholder)
PHP Example - AJAX Live Search
AJAX can be used to create more user-friendly and interactive searches.
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AJAX Live Search
The following example will demonstrate a live search, where you get search results while you type.
Live search has many benefits compared to traditional searching:
• Results are shown as you type
• Results narrow as you continue typing
• If results become too narrow, remove characters to see a broader result
Search for a W3Schools page in the input field below:
The results in the example above are found in an XML file (links.xml). To make this example small and simple, only eight results are available.
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Example Explained - The HTML Page
When a user types a character in the input field above, the function "showResult()" is executed. The function is triggered by the "onkeyup" event:
Source code explanation:
If the input field is empty (str.length==0), the function clears the content of the livesearch placeholder and exits the function.
If the input field is not empty, the showResult() function executes the following:
• Create an XMLHttpRequest object
• Create the function to be executed when the server response is ready
• Send the request off to a file on the server
• Notice that a parameter (q) is added to the URL (with the content of the input field)
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The PHP File
The page on the server called by the JavaScript above is a PHP file called "livesearch.php".
The source code in "livesearch.php" searches an XML file for titles matching the search string and returns the result:
load("links.xml");
$x=$xmlDoc->getElementsByTagName('link');
//get the q parameter from URL
$q=$_GET["q"];
//lookup all links from the xml file if length of q>0
if (strlen($q)>0)
{
$hint="";
for($i=0; $i<($x->length); $i++)
{
$y=$x->item($i)->getElementsByTagName('title');
$z=$x->item($i)->getElementsByTagName('url');
if ($y->item(0)->nodeType==1)
{
//find a link matching the search text
if (stristr($y->item(0)->childNodes->item(0)->nodeValue,$q))
{
if ($hint=="")
{
$hint="" .
$y->item(0)->childNodes->item(0)->nodeValue . "";
}
else
{
$hint=$hint . "
" .
$y->item(0)->childNodes->item(0)->nodeValue . "";
}
}
}
}
}
// Set output to "no suggestion" if no hint were found
// or to the correct values
if ($hint=="")
{
$response="no suggestion";
}
else
{
$response=$hint;
}
//output the response
echo $response;
?>
If there is any text sent from the JavaScript (strlen($q) > 0), the following happens:
• Load an XML file into a new XML DOM object
• Loop through all