AMSOL e-Tutor

Variables

Variables are most important elemenants of any program, these are containers for storing information, it can be number, text or alpha-numeric. In PHP every variable starts with $ symbol. After $ only alphbets are allowed and after 1st alphabet numbers can be used, variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ ).

$x and $X are 2 different variables.

example:

$x = 5;
$y = 10;
$z = $x * $y;

Output Variables: Variables are manipulated within program and where ever output display is required, echo statement comes in to place. echo $y;

semi colon ; sign has special meaning in PHP, it is equivalent to full stop in grammar. It means statement has completed. We can write program in continuous mode like $x = 5; $y = 10; $z = $x * $y;

For better readability we can write code as

$x = 5;
$y = 10;
$z = $x * $y;

Variables Scope

PHP has three different variable scopes:

local
global
static

global: All declared variables have global scope, unless declared within a function.

local: A variable declared within a function has a LOCAL SCOPE and can only be accessed within the function.

static: When a function is executed, all of its variables are deleted. if we want a local variable NOT to be deleted we use static variable.

To do this, use the static keyword when you first declare the variable:

static $x = 0;

Variable Data Types

PHP supports the following data types:

String Integer Float (floating point numbers - also called double) Boolean Array Object NULL Resource