PHP - SPLessons

PHP Variables

Chapter 6

SPLessons 5 Steps, 3 Clicks
5 Steps - 3 Clicks

PHP Variables

PHP Variables

shape Description

PHP Variables are nothing but a named storage locations in the memory.

Declaring Variables:

There is no need to declare the variable type in advance.In other programming languages, the variable name, data type has to be declared before using it.But in PHP, types are associated with the values so declaration is not necessary.The initial step while using a variable is value assignment.

Assigning Variables:

Assigning a variable is easy.Write the name and add a single equal sign = and then the expression that has to be assigned a variable.For example, Eg: $pi=3+0.1489.

Generally Variables in PHP are defined by ” $” symbol followed by name of the Variable. Variables in PHP are case sensitive.

shape Syntax

$x , $y, $Name .. etc.,

shape Example

<!DOCTYPE html>
<html>
    <body>
     
        <?php 
        $x = "Welcome to Splessons"; 
        $y = 30; $z= 70; 
        echo "x is :".$x." <br>"; 
        echo "y is :".$y." <br> "; 
        echo "z is :".$z; 
        ?>
     
    </body>
</html>

Output:

Standard Rules for Defining Variables

shape Description

PHP -User Friendly Language

In PHP, there is need to declare the datatype of the variable, according to the assigned value. Automatically datatype of the variable will be assigned.

PHP Variable Scope

shape Description

Scope is nothing but the rules when a name in two different places has the same meaning. PHP has four different variable scopes depending on the variable defined location.

shape Conceptual
figure

Local Variable Scope

shape Description

Local variables are defined and accessed within the function. They are not accessible outside the function.

shape Program
Description

shape Example

<!DOCTYPE html>
<html>
	<body>

		<?php 
		function myVariables() 
		{ 
		$age = 25; // local scope 
		echo "The Variable age defined inside the function and the value is: ".$age." <br><br>"; 
		} 
		myVariables(); // if you call the age variable outside function, will give an error 
		echo "The Variable age outside function is: ".$age.""; 
		?>

	</body>
</html>

Output:

Output:

The Variable age defined inside the function and the value is: 25 

Global Variable Scope

shape Description

Global variables are defined outside of the function.One can access the global variables anywhere in the script, outside the function.

But, global variables can also be accessed inside the function also, by using the keyword global before the variable declaration.

shape Program
Description

shape Example

<!DOCTYPE html>
<html>
<body>
  <?php 
    $a = 60; 
    $b = 95; 
    function myVariables() { 
    global $a, $b; 
    $b = $a + $b; 
    } 
    myVariables(); 
    echo $b; // global variable accessing outside the function 
    ?>
</body>
</html>

Output:

Static Variable Scope

shape Description

Generally, after the execution of function is completed, the variables and the values in the variable will be deleted.But some times, local variable should not be deleted and should work in further execution also.For that, use the keyword static. Static is kept before the variable, at the first time of declaration.

shape Example

<!DOCTYPE html>
<html>
    <body>
        <?php 
            $a = 60; 
            $b = 95; 
            
            function myVariables() { 
            static $a, $b; 
            $b = $a + $b; 
            }
             
            myVariables();
            echo "The valuse of b is:". $b;
        ?>
    </body>
</html>

Output:

Summary

shape Key Points

  • PHP Variables are defined by ” $” symbol.
  • Local variables are not accessible outside the function.
  • Global variables are accessed anywhere inside the script.
  • Static variables does not delete the local functionality of a variable and works even after execution.