The $var (single dollar) is a normal variable with the name var that stores any value like string, integer, float, etc.
$$varTo understand the difference better, let's see some examples.
<?php $x = "abc"; $$x = 200; echo $x."<br/>"; echo $$x."<br/>"; echo $abc; ?>
Output:
In the above example, we have assigned a value to the variable x as abc. Value of reference variable $$x is assigned as 200.
Now we have printed the values $x, $$x and $abc.
<?php $x="U.P"; $$x="Lucknow"; echo $x. "<br>"; echo $$x. "<br>"; echo "Capital of $x is " . $$x; ?>
Output:
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.
<?php
$name="Cat";
${$name}="Dog";
${${$name}}="Monkey";
echo $name. "<br>";
echo ${$name}. "<br>";
echo $Cat. "<br>";
echo ${${$name}}. "<br>";
echo $Dog. "<br>";
?>Output:
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.
