PHP Tutorial Part 8 : PHP - $ and $$ Variables

 PHP $ and $$ Variables

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:

ABC

200

200

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.

---

Example-2

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

Output:

U.P

Lucknow

Capital of U.P in Lucknow

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.

---

Example-3

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

Output:

Cat

Dog

Dog

Monkey

Monkey

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.

---