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PHP: Incrementing Decrementing Operators

Description

PHP supports C-style pre and post increment and decrement operators. The Increment/decrement operators operate only on variables and not on any value.

List of increment/decrement operators

Example Name Effect
++$x Pre-increment Increments $x by 1, then returns $x.
$x++ Post-increment Returns $x, then increments $x by 1.
--$x Pre-decrement Decrements $x by 1, then returns $x.
$x-- Post-decrement Returns $x, then decrements $x by 1.

Example:

<?php
$a = 10;
echo 'Value of $a is :'.$a;
echo '<br />After Pre-increment value of $a ( i.e. ++$a ) is: '.++$a;
$a = 20;
echo '<br />Value of $a is :'.$a;
echo '<br />After Post-increment value of $a ( i.e. $a++ ) is: '.$a++;
$a = 30;
echo '<br />Value of $a is :'.$a;
echo '<br />After Pre-decrement value of $a ( i.e. --$a ) is: '.--$a;
$a = 40;
echo '<br />Value of $a is :'.$a;
echo '<br />After Post-decrement value of $a ( i.e. $a-- ) is: '.$a--;
?>

Output:

Value of $a is :10
After Pre-increment value of $a ( i.e. ++$a ) is: 11
Value of $a is :20
After Post-increment value of $a ( i.e. $a++ ) is: 20
Value of $a is :30
After Pre-decrement value of $a ( i.e. --$a ) is: 29
Value of $a is :40
After Post-decrement value of $a ( i.e. $a-- ) is: 40

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PHP: Tips of the Day

In PHP, there are two versions of logical AND and OR operators.

Operator True if
$a and $b Both $a and $b are true
$a && $b Both $a and $b are true
$a or $b Either $a or $b is true
$a || $b Either $a or $b is true

Note that the && and || opererators have higher precedence than and and or. See table below:

Evaluation Result of $e Evaluated as
$e = false || true True $e = (false || true)
$e = false or true False ($e = false) or true

Because of this it's safer to use && and || instead of and and or.