What does the modulus do?

Question

I never really get it, but what does the modulus operator (%) do.

And when would you want to use it in a mathematical context? By the way, I

just want to know what it does, not how it works.

Did you miss how to do manual division in elementary school somehow? — πάντα ῥεῖ, Oct 24 '15 at 21:35
Is it me in question? It's you who was asking for something trivial. — πάντα ῥεῖ, Oct 24 '15 at 21:48
It's all well [documented](http://en.cppreference.com/w/cpp/utility/functional/modulus). No need to ask here. — πάντα ῥεῖ, Oct 24 '15 at 21:53
The mod operator basically means "remainder after division". For example, `11 % 3 == 2` (because `11 == 3*3 + 2`). Another example: `25 % 7 == 4` (because `25 == 7*3 + 4`). HTH — Stuart Berg, Oct 24 '15 at 22:47
Possible duplicate of [How Does Modulus Divison Work](http://stackoverflow.com/questions/2664301/how-does-modulus-divison-work) — Nate Barbettini, Oct 25 '15 at 00:20
I'm voting to close this question as off-topic because it is about mathematics, not programming. — High Performance Mark, Oct 31 '15 at 18:02

score 4 · Accepted Answer · answered Oct 24 '15 at 21:10

4

It calculates the remainder of a division operation.

5 / 2 == 2   // whole part of the division
5 % 2 == 1   // remainder

In other words you could reconstruct the original number by

2 * 2 + 1 == 5
|   |   ^ remainder
|   ^ whole part
^ divisor

answered Oct 24 '15 at 21:10

Cory Kramer

Wow, thanks alot. I kind of get it now! – Samuel L. Oct 24 '15 at 21:20
But how exactly do you use it? – Samuel L. Oct 24 '15 at 21:46
1

What do you mean how do you use it? It is an arithmetic operator, you use it the same way you would use `+`, `-`, `*`, `/`, etc. For example `int remain = 5 % 2;` – Cory Kramer Oct 24 '15 at 22:04
@SamuelL. for example if you wanted to check if a number was even you could say does `x%2==0` or "if I divide by 2 is there NO (0) remainder. – Albert Renshaw Oct 24 '15 at 22:59
Thanks for the help! – Samuel L. Oct 24 '15 at 23:33

1 Answers1