PHP $ and $$ variables

In this tutorial, you will learn about the differences between $var and $$var in PHP.

The $var(Single Dollar) is the normal PHP variable with the name var that stores numeric and non-numeric values like integer, double, string, etc.

The $$var(Double variable) is the reference variable that stores the value of $var into it.

This enables you to have a variable’s variable and store the reference of another variable. Without much delay, let’s understand the difference with the help of some examples.

Example 1: PHP $ and PHP $$

<?php 
$var = "xyz"; 
$$var = 200; 
echo $var."<br/>"; 
echo $$var."<br/>"; 
echo $xyz; 
?>

Output

In the above example, we have assigned a variable $var with the value xyz and reference variable $$var assigned with 200. Now, we have printed the value of $var, $$var, and $xyz.

Note: Reference variable $$var can be accessed by putting $ before the value of $var. In this case $xyz.

Example 2

<?php
$x = "Maharashtra";
$$x = "Mumbai";
echo $x."<br/>";
echo $$x."<br/>";
echo "Capital of $x is :".$$x;
?>

Output

In the above example, we have assigned the value to the variable x as “Maharastra” and the value of the reference variable as “Mumbai”.

Now we have printed the value of $x and $$x using PHP Echo statement.

Example 3

<?php
$name="Sagar";
${$name}="Sajal";
${${$name}}="Shankar";
echo $name. "<br>";
echo ${$name}. "<br>";
echo $Sagar. "<br>";
echo ${${$name}}. "<br>";
echo $Sajal. "<br>";
?>

Output

In the above example, we have assigned a value to the variable as Sagar. Value of reference variable ${$name} is assigned as Sajal and reference variables of the variable are assigned as Shankar.

Now, we have printed the values of $name, ${$name}, $Sagar, ${${$name}} and $Sajal.