PHP | $ vs $$ operator

The $ operator in PHP is used to declare a variable. In PHP, a variable starts with the $ sign followed by the name of the variable. For example, below is a string variable:

$var_name = "Hello World!";

The $var_name is a normal variable used to store a value. It can store any value like integer, float, char, string etc. On the other hand, the $$var_name is known as reference variable where $var_name is a normal variable. The $$var_name used to refer to the variable with the name as value of the variable $var_name. Examples:

Input :  $Hello = "Geeks for Geeks"
         $var = "Hello"
         echo $var
         echo $$var
Output : Hello
         Geeks for Geeks

Input :  $GFG = "Welcome to GeeksforGeeks"
         $var = "GFG"
         echo $var
         echo $$var
Output : GFG
         Welcome to GeeksforGeeks

Explanation: In the above example, $var stores the value "Hello", so $$var will refer to the variable with name Hello i.e., $Hello. Below program will illustrate the $ and $$ operator in PHP. php

<?php

// Variable declaration and initialization 
$var = "Hello";
$Hello = "GeeksforGeeks";

// Display the value of $var and $$var
echo $var . "\n";
echo $$var;

echo "\n\n";

// Variable declaration and initialization 
$var = "GFG";
$GFG = "Welcome to GeeksforGeeks";

// Display the value of $var and $$var
echo $var. "\n";
echo $$var;
?>