How does java do modulus calculations with negative numbers?

Question

Am I doing modulus wrong? Because in Java `-13 % 64` evaluates to `-13` but I want to get `51`.

Accepted Answer

Both definitions of modulus of negative numbers are in use - some languages use one definition and some the other.

If you want to get a negative number for negative inputs then you can use this:

```
int r = x % n;
if (r > 0 && x < 0)
{
    r -= n;
}
```

Likewise if you were using a language that returns a negative number on a negative input and you would prefer positive:

```
int r = x % n;
if (r < 0)
{
    r += n;
}
```

Solution