PHP Variables

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Variables are reserved memory locations for storing data values.

In PHP, all variables starts with the $ sign, followed by the name of the variable.

A variable name must start with a letter or the underscore character

A variable name cannot start with a number

A PHP variable name cannot contain spaces.

A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )

PHP variable names are case-sensitive.($code and $CODE are two different variables)

Assignment of variables are done with assignment operator, “equal to (=)”.

PHP is a loosely typed language, it means PHP automatically converts the variable to its correct data type.

Let's see the example to store string, integer, and float values in PHP variables.

Example : Declaring string, integer, and float


<?php  
$str="hello string";  
$x=123;  
$y=345.6;  
echo "string is: $str 
";  
echo "integer is: $x 
";  
echo "float is: $y 
";  
?>

Global Scope

A variable declared outside a function has a Global Scope and can only be accessed outside a function

Example : Global Scope


 <?php              
 $x = 78; // global scope
 function myTest() {
   echo "Variable x inside function is: $x";
 } 
 myTest();
 echo "Variable x outside function is: $x";
 ?>

use the global keyword to access a global variable from within a function.

Example : Global Keyword


 <?php              
 $x = 78; // global scope
 function myTest() {
    global $x;
   echo "Variable x inside function is: $x";
 } 
 myTest();
 echo "Variable x outside function is: $x";
 ?>

Local Scope

A variable declared within a function has a Local Scope and can only be accessed within that function:

Example : Local Scope


 <?php              
 function myTest() {
    $x = 78; // local scope 
   echo "Variable x inside function is: $x";
 } 
 myTest();
 echo "Variable x outside function is: $x";
 ?>