PHP Functions
The real power of PHP comes from its functions.
In PHP, there are more than 700 built-in functions.
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 browser from executing a script when the page loads, you can put
your script into a function.
A function will be executed by a call to the function.
You may call a function from anywhere within a page.
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:
<html>
<body>
<?php
function writeName()
{
echo "Kai Jim Refsnes";
}
echo "My name is ";
writeName();
?>
</body>
</html>
|
Output:
|
My name is Kai Jim Refsnes |
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:
<html>
<body>
<?php
function writeName($fname)
{
echo $fname . " Refsnes.<br />";
}
echo "My name is ";
writeName("Kai Jim");
echo "My sister's name is ";
writeName("Hege");
echo "My brother's name is ";
writeName("Stale");
?>
</body>
</html>
|
Output:
My name is Kai Jim Refsnes.
My sister's name is Hege Refsnes.
My brother's name is Stale Refsnes.
|
Example 2
The following function has two parameters:
<html>
<body>
<?php
function writeName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "<br />";
}
echo "My name is ";
writeName("Kai Jim",".");
echo "My sister's name is ";
writeName("Hege","!");
echo "My brother's name is ";
writeName("Ståle","?");
?>
</body>
</html>
|
Output:
My name is Kai Jim Refsnes.
My sister's name is Hege Refsnes!
My brother's name is Ståle Refsnes?
|
PHP Functions - Return values
To let a function return a value, use the return
statement.
Example
<html>
<body>
<?php
function add($x,$y)
{
$total=$x+$y;
return $total;
}
echo "1 + 16 = " . add(1,16);
?>
</body>
</html>
|
Output:
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