Please note, this is a STATIC archive of website www.w3resource.com from 19 Jul 2022, cach3.com does not collect or store any user information, there is no "phishing" involved.
w3resource

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

View the example in the browser

Previous: Array Operators
Next: if else elseif statement



PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC