The assignment operator (=) assigns the value, or expression, to the variable; and yes, it’s different from the equality comparison operator (==). This is one of the most commonly made mistakes for beginner programmers: using the assignment operator when a comparison operator is required.

The following syntax is required for the PHP assignment operator:

$variable = value (or expression)

The assignment takes the expression on the right and assigns it to the variable on the left.

<?php// Assign a value to a variable
$best_php_tutorial_youtuber = "Dino Cajic"; // of course// Assign an expression to a variable
$best_expression = 5 + 7;/** Another expression
 *  These two strings are concatenated
 *  and are then assigned to the 
 *  variable on the left.
 */
$another_expression = "Hello " . "there";?>

This is where it starts getting a little weird. You can assign a value to a variable and then assign that variable to another variable. You can keep going as many times as you want, but the code readability will suffer.

<?php$x = ($y = 2) + 22;?>

Let’s see how PHP would process the assignment operator example above:

1. PHP starts by assigning the value 2 to the variable $y.
2. A new expression is formed: $y + 22.
3. That expression is evaluated. The value 2 is substituted for $y and is then added to 22:2 + 22 = 24.
4. The new value, 24, is assigned to $x. Variable $x now contains the value 24.

We can now use both the $x and $y variables.

<?phpecho $x; // prints 24
echo $y; // prints 2?>

For readability purposes, I suggest that you’re as explicit as possible when assigning values to variables. The following code is a lot easier to read than what we did in the previous example.

<?php$y = 2;
$x = $y + 22;?>