在一系列数字中加上和减去并循环

Question

I'm wondering how I would go about the addition and subtraction of numbers in a set range and which would loop back on themselves, example below;

Range: 1 - 10

So if I now had the number 7 and added 5 to it, I would want the number go to 2

8, 9, 10, loop around to 1, 2.

And the same if I subtracted, so I have the number 3 and I subtract 4 so I should be left with 9.

2, 1, loop around to 10, 9

I hope this makes sense.

Thanks.

Answer 1

You can use % operator.

It calculates remainder after division.

For example:

$d = 10;

$x = 7;

$y = 5;

echo ($x + $y) % $d;

gives 2;

With negative values you can just remove MINUS