PHP Tutorial - Lesson 3: Introduction to PHP - Part IV

Functions

•          Latest topic to be discussed in this lesson is functions.

•          The real power of PHP comes from its functions.

•          In PHP there are more than 700 built-in functions.

•          In previous lessons, we discussed some of built-in functions that php offers, such as function time, date, isset, unset, session_start(), mb_strstr, mb_strlen… etc.

•          Now we are going to discuss, user-defined functions, which you are as a programmer build it yourself.

•          Functions have an advantage of keeping the browser from executing your script while page loading. How? When you put your script in a function, then it will be executed only when you call the function.

How to create a function?

•          Syntax:

•          function functionName()

•          {

•          Code to be executed.

•          }

Example:

<?php

function printName($var)

{

echo “<font style=‘font-size:14px’> $var.”</font><Br>”;

}

?>

Function Returns a value:

<?php

function sum($var1,$var2)

{
return $var1 + $var2;

}

?>

How to call a function?

<?php

function welcomeMessage()

{

echo “Welcome to my application”;

}

welcomeMessage();

?>

•          If the function returns a value, then the function can be called by storing its return value in a variable, or directly echo-ing it.

Example:

<?php

function sum($v1,$v2)

{

$s = $v1 + $v2;

return $s;

}

$x = sum(1,2); // $x = 3

echo sum(2,3); // will print 5

?>

End of lesson 3, to download this lesson as PDF click here: PHP Tutorial - Lesson 3: Introduction to PHP - Part IV

Best Wishes,

Anas Jaghoub