PHP Variables

By Aastha Tyagi Last updated Nov 28, 2017 0

In simple words, a variable is a name of memory location that holds data. A variable is a temporary storage that is used to store data temporarily.

What is Variables in PHP

Areas of memory set aside by the programmer to store data and assigned a name by the programmer. These variables can then be used for such things as temporary storage during calculations.
A PHP variable starts with the $ sign, followed by the name of the variable.
Variables works as containers for storing data.
A variable name can not start with a number.
Variable name are case-sensitive(ex: $color, $COLOR both are different).
Variable can contains alpha-numeric values and special symbols.
PHP variables must start with letter or underscore

EXAMPLE-

<?php
$x = 5;
$y = 6;
echo $x * $y;
?>

OUTPUT:
30

Loosely Typed Language
PHP is a loosely typed language because its automatically converts variable to correct data-types.
In other languages such as C, C++, and Java, it is must to declare the name and type of the variable before using it.

Variable Declaration

  $variable_name = value;

Variable Scope

Scope can be defined range of availability.Variables can be declared anywhere in the script.There are 3 type of variables in PHP.

local variable
global variable
static variable

Local Variable – A Local variable declared inside a function.These variables have local scope and can not be accessed outside a function.

<?php
function testFunction() {
    $var = 10; // local scope
    echo "<p>Variable var inside function is: $var</p>";
}
testFunction();
echo "<p>Variable var outside function is: $var</p>";
?>

OUTPUT:
Variable var inside function is: 10
Variable var outside function is:

Global Variable – A Global variable declared outside a function.These variables have Global scope and can only be accessed outside a function.

<?php
$var = 10; // global scope
function testFunction() {
   echo "<p>Variable var inside function is: $var</p>";
} 
testFunction();
echo "<p>Variable var outside function is: $var</p>";
?>

OUTPUT: 
Variable var inside function is:
Variable var outside function is: 10

Static Variable –When a function is executed, its all variables are deleted. However, we want a local variable NOT to be deleted. We need it for a further job.
You can declare a variable to be static simply by placing the keyword STATIC in front of the variable name.

<?php
function testFunction() {
    static $x = 10;
    echo $x;
    $x--;
}

testFunction();
echo "<br>";
testFunction();
echo "<br>";
testFunction();
?>

OUTPUT:
10
9
8