PHP function

The real power of PHP comes from its functions.

In PHP, more than 1000 built-in functions are provided.

PHP built-in functions

For a complete reference manual and examples of all array functions, visit our PHP Reference Manual.

PHP functions

In this chapter, we'll show you how to create your own functions.

To execute a script when the page loads, you can put it inside a function.

Functions are executed by calling functions.

You can call functions anywhere on the page.

Create PHP function

Functions are executed by calling functions.

 <?php function functionName ( ) {    // Code to be executed } ?>

PHP function guidelines:

The name of the function should suggest what it does

Function name starts with a letter or underscore (cannot start with a number)

Example

A simple function that prints my name when called:

 <? php function writeName (){ echo " Kai Jim Refsnes " ;} echo " My name is " ; writeName (); ?>

Output:

 My name is Kai Jim Refsnes

PHP Function - Add Parameters

To add more functionality to a function, we can add parameters. Parameters are like variables.

Parameters are specified within parentheses just after the function name.

Example 1

The following example will output different first names, but the same last name:

 <? 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 " ); ?>

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 takes two parameters:

 <? 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 " , " ? " ); ?>

Output:

 My name is Kai Jim Refsnes.My sister's name is Hege Refsnes!My brother's name is Ståle Refsnes?

PHP function - return value

To have a function return a value, use the return statement.

 <? php function add ($ x ,$ y ){ $ total =$ x +$ y ; return $ total ;} echo " 1 + 16 = " . add ( 1 , 16 ); ?>

Output:

 1 + 16 = 17