Incrementing / Decrementing a Number by a Number with PHP

Josh Sherman
1 min read
Software Development PHP

We’ve previously discussed how to simply increment and decrement a variable but that only covered incrementing by a value of 1. What about when you want to increment a variable by 5s? There’s a few different ways this can be accomplished. First, the obvious (albeit far from ideal) using ++ 5 times:

$i = 0;

$i++;
$i++;
$i++;
$i++;
$i++;

echo $i; // 5!

I know, that’s silly, but I’m sure someone out there has done it before. Now let’s get serious, to increment a variable by 5 you can use +=, which is similar to ++ but allows you specify the value to increment by:

$i  = 0;
$i += 5;

echo $i; // Still 5!

Decrementing works in quite the same way but, you guessed it, uses -= instead:

$i  = 10;
$i -= 5;

echo $i; // 5, yet again!

The use of += and -= is the shorthand equivalent of the following syntax:

$i = $i + 5;
$j = $j - 5;

If you ever run into (or already have run into) the first example of multiple ++ or --s please please please leave a comment below!

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Husband. Father. Pug dad. Born again Linux user. Founder of Holiday API, Backend Engineering Manager and Emoji Specialist at Mailshake, and author of the best damn Lorem Ipsum Library for PHP.

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