PHP numbers logic

Question

I just started to learn PHP deeper for Zend PHP certification and I found this code, which actually works. Can someone explain me the logic behind this?

<?php
$num = 20% - 8;
echo $num; // 4

% is not per cent, but modulus, cf. https://en.m.wikipedia.org/wiki/Modular_arithmetic — MrTux, Jul 10 '19 at 06:30

score 2 · Accepted Answer · answered Jul 10 '19 at 06:32

What you're seeing is the modulus operator, which in essence asks "What is the remainder of 20 divided by -8".

So you might ask, why isn't it negative 4? From the manual,

The result of the modulo operator % has the same sign as the dividend — that is, the result of $a % $b will have the same sign as $a.

See the PHP: Arithmetic Operators for more documentation.

score 1 · Answer 2 · answered Jul 10 '19 at 06:32

1

% is not per cent, but modulus, cf. https://en.m.wikipedia.org/wiki/Modular_arithmetic

20 = 2 * 8 + 4, therefore, 20 % 8 = 4

answered Jul 10 '19 at 06:32

MrTux

30,335
25
102
137

PHP numbers logic

2 Answers2