PHP - decrement operator

The decrement (--) is an unary operator in PHP and hence acts upon a single operand to produce a new value. It has two variant:

• Pre-decrement: Decreases the value of the operand by 1, then returns the operand.
• Post-decrement: Returns the operand, then decreases the value of the operand by 1.

Example: Pre-decrement operator

The example below describes the usage of pre-decrement operator.

<?php
$x = 10;
$y = 20;

//below expression is equivalent to
//$x = $x - 1; $z = $x + $y;
$z = --$x + $y;    

//Displaying the result
echo "x = $x\n";
echo "y = $y\n";
echo "z = $z\n";
?>

The output of the above code will be:

x = 9
y = 20
z = 29

Example: Post-decrement operator

The example below describes the usage of post-decrement operator.

<?php
$x = 10;
$y = 20;

//below expression is equivalent to
//$z = $x + $y; $x = $x - 1; 
$z = $x-- + $y;    

//Displaying the result
echo "x = $x\n";
echo "y = $y\n";
echo "z = $z\n";
?>

The output of the above code will be:

x = 9
y = 20
z = 30