PHP Functions
The real power of PHP comes from its functions.
In PHP - there are more than 700 built-in functions available.
PHP Functions
In this tutorial we will show you how to create your own functions.
For a reference and examples of the built-in functions, please visit our
PHP Reference.
Create a PHP Function
A function is a block of code that can be executed whenever we need it.
Creating PHP functions:
- All functions start with the word "function()"
- Name the function - It should be possible to understand what the
function does by its name. The name can start with a letter or
underscore (not a number)
- Add a "{" - The function code starts after the opening
curly brace
- Insert the function code
- Add a "}" - The function is finished by a closing curly brace
Example
A simple function that writes my name when it is called:
<html>
<body>
<?php
function writeMyName()
{
echo "Kai Jim Refsnes";
}
writeMyName();
?>
</body>
</html>
|
Use a PHP Function
Now we will use the function in a PHP script:
<html>
<body>
<?php
function writeMyName()
{
echo "Kai Jim Refsnes";
}
echo "Hello world!<br />";
echo "My name is ";
writeMyName();
echo ".<br />That's right, ";
writeMyName();
echo " is my name.";
?>
</body>
</html>
|
The output of the code above will be:
Hello world!
My name is Kai Jim Refsnes.
That's right, Kai Jim Refsnes is my name.
|
PHP Functions - Adding parameters
Our first function (writeMyName()) is a very simple function. It only writes a
static string.
To add more functionality to a function, we can add parameters. A parameter is just like a variable.
You may have noticed the parentheses after the function name,
like: writeMyName(). The parameters are specified inside the parentheses.
Example 1
The following example will write different first names, but the same last
name:
<html>
<body>
<?php
function writeMyName($fname)
{
echo $fname . " Refsnes.<br />";
}
echo "My name is ";
writeMyName("Kai Jim");
echo "My name is ";
writeMyName("Hege");
echo "My name is ";
writeMyName("Stale");
?>
</body>
</html>
|
The output of the code above will be:
My name is Kai Jim Refsnes.
My name is Hege Refsnes.
My name is Stale Refsnes.
|
Example 2
The following function has two parameters:
<html>
<body>
<?php
function writeMyName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "<br />";
}
echo "My name is ";
writeMyName("Kai Jim",".");
echo "My name is ";
writeMyName("Hege","!");
echo "My name is ";
writeMyName("Ståle","...");
?>
</body>
</html>
|
The output of the code above will be:
My name is Kai Jim Refsnes.
My name is Hege Refsnes!
My name is Ståle Refsnes...
|
PHP Functions - Return values
Functions can also be used to return
values.
Example
<html>
<body>
<?php
function add($x,$y)
{
$total = $x + $y;
return $total;
}
echo "1 + 16 = " . add(1,16);
?>
</body>
</html>
|
The output of the code above will be:
 |
|
Get Your Diploma!
W3Schools' Online Certification Program is the perfect solution for busy
professionals who need to balance work, family, and career building.
The HTML Certificate is for developers who want to document their knowledge of HTML, XHTML, and CSS.
The JavaScript Certificate is for developers who want to document their knowledge of JavaScript and the HTML DOM.
The XML Certificate is for developers who want to document their knowledge of XML, XML DOM and XSLT.
The ASP Certificate is for developers who want to document their knowledge of ASP, SQL, and ADO.
The PHP Certificate is for developers who want to document their knowledge of PHP and SQL (MySQL).
|
| 
