PHP Built-in Functions

PHP Functions

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

To keep the script from being executed when the page loads, you can put it 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:

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

Output:

My name is Kai Jim Refsnes

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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:

function writeName($fname) { echo $fname . " Refsnes. "; } 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 has two parameters:

function writeName($fname,$punctuation) { echo $fname . " Refsnes" . $punctuation . " "; } 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?

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PHP Functions - Return values

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

Example

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

Output:

1 + 16 = 17