Variables in PHP

Variables are used in a program to store some value or data which can be used later in the program.PHP is a loosely typed language.
1. No fixed data type to a variable
2. Variables can contain any value – number, string or reference
3. Arrays are special variables to hold multiple values
4. Variables are preceded with $
5. PHP is case sensitive. $x is different from $X

Syntax

Syntax of declaring a variable in PHP is given below:

<?php
    $variablename=value;  
?>

Example

<?php
       $x=10;               # integer assignment
       $x="string here";    # string assignment
       $x=10.25;            # double/float assignment
       $x=TRUE;             # boolean Value
?>

No fixed size of memory : No need to declare a variable. Memory is allocated at the time of initialization. Unlimited memory. Memory grows and shrinks automatically.

<?php
       $x="abc";                          #3 character string
       $x="this is a bigger string";      # a bigger string assigned
?>

Automatic type conversion

The type of the value is temporarily auto converted to type required in the current expression. String to numeric conversion results in a number, if the string is starting with a number. If the string is not starting with a number it results in 0.

<?php
    $x="10"; 
    echo $x+20;        #prints 30 as $x is assumed as 10
?>

PHP Variables Scope

In PHP, variables can be declared anywhere in the script. The scope of a variable is the part of the script where the variable can be referenced/used. There are three different variable fields in PHP:
Local Variables: Variables declared within a function are called local variables for that function and have scope only in that particular function.
Global Variables: Variables declared outside a function are called global variables. These variables can be accessed directly outside a function.
Static Variables: It is the feature of PHP to delete the variable, once its execution is completed and the memory is freed.

<?php
    $a = 5; // global scope
    function myTest() {
        $b = 5; // local scope
        static $c = 0; //static scope
    }
    myTest();
?>

PHP Variable: Sum of two variables

#Source Code
<?php
    $a=5;  
    $b=6;  
    $c=$a+$b;  
    echo $c;  
?>
#Output
11

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