The $var (single dollar) is a normal variable with the name var that stores any value like string, integer, float, etc.

The $$var (double dollar) is a reference variable that stores the value of the $variable inside it.

To understand the difference better, let’s see some examples.

Example 1

 <?php
$x = “abc”;
$$x = 200;
echo $x.“<br/>”;
echo $$x.“<br/>”;
echo $abc;
?>

Output:

PHP $ and $$ variables 1

In the above example, we have assigned a value to the variable x as abc. Value of reference variable $$x is assigned as 200.

Now we have printed the values $x, $$x and $abc.

Example2

<?php
 $x=“U.P”;
$$x=“Lucknow”;
echo $x. “<br>”;
echo $$x. “<br>”;
echo “Capital of $x is “ . $$x;
?>

Output:

PHP $ and $$ variables 2

In the above example, we have assigned a value to the variable x as U.P. Value of reference variable $$x is assigned as Lucknow.

Now we have printed the values $x, $$x and a string.

Example3

<?php
$name=“Cat”;
${$name}=“Dog”;
${${$name}}=“Monkey”;
echo $name. “<br>”;
echo ${$name}. “<br>”;
echo $Cat. “<br>”;
echo ${${$name}}. “<br>”;
echo $Dog. “<br>”;
?>

Output:

PHP $ and $$ variables 3

In the above example, we have assigned a value to the variable name Cat. Value of reference variable ${$name} is assigned as Dog and ${${$name}} as Monkey.

Now we have printed the values as $name, ${$name}, $Cat, ${${$name}} and $Dog.