Functions

Function is a code block that executes certain task.

Syntax

function funcName(args) { // Code to execute. }

Void Example

A void function doesn't return any value.

Example:

<?php // Calling a function: printHi(); function printHi() { echo "Hi!"; }

Output:

Hi!

Returning Result

Via the return keyword a result can be returned.

Let's have an example in which rectangle's area is calculated by passing arguments about it's sides.

Example:

<?php $area = calcRectangleArea(3, 4); echo $area; function calcRectangleArea($widthArg, $heightArg) { return $widthArg * $heightArg; }

Output:

12

There are couple of things to mark:

• A functions is defined at lines 5 - 7. It accepts two arguments - widthArg and heightArg.
• The function calcRectangleArea returns a result.
• calcRectangleArea is called at line 2.
• It's returned value is set in the variable area.

Arguments Count Mismatch

If arguments count is mismatched an exception is thrown.

<?php calcTrapezoidArea(3, 4); function calcTrapezoidArea($a, $b, $h) { return ($a + $b) / 2 * $h; }

The function calcTrapezoidArea expects 3 arguments but only 2 are passed to it thus exception is thrown.

Default Value

Default value may be specified for function parameters.

Let's look at the following:

<?php printArg(5); echo "<br>"; // Print new line. printArg(); function printArg($arg = 3) { echo $arg; }

Output:

5 3

At line 5 the function argument is not passed thus it takes the default value - 3 specified at line 7.