|
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:
|
