PHP 5 Functions

The true 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, please visit our PHP Reference Manual .

PHP functions

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

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

The function is executed by calling the function.

You can call functions anywhere on the page.


The function is executed by calling the function.

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

PHP function guidelines:

  • The name of the function should suggest its function
  • The function name starts with a letter or underscore (cannot start with a number)


A simple function that outputs my name when called:


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


My name is Kai Jim Refsnes

PHP functions-add parameters

In order to add more functions to the function, we can add parameters, which are similar to variables.


parameter is specified in parentheses after the function name.

Instance 1

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


<?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"); ?>


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:


<?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","?"); ?>


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 make a function return a value, use a return statement.


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


1 + 16 = 17