On Sep 25, 11:11 am, "Michel Walsh"
<vanderghast@VirusAreFunnierThanSpamwrote:
Mathematically, r = a modulo b (b being the divisor) is defined such
that if b <0, and if r <>0, its sign should be the sign of b.
C# does not follow this definition.
int indx = -1;
indx %= 100;
will let indx == -1, not == 99 as it should (mathematical definition).
Is that "by specification"? and if so, is there an alternate predefined
'modulo' operator which behaves like the mathematical definition?
C# takes the sign of the dividend, not divisor. (There is another
thread recently discussing this very thing).
a = dividend;
n = divisor;
r = a - n * Floor(a / n) when result of a/n is positive
r = a - n * Cieling(a / n) when result of a/n is negative.
As a result of this, r takes the sign of the dividend...
Besides, longhand, the remainder comes up -1 <g>
-1 % 100 = -1:
___0_____
100 | -1
0
______
-1 <--- remainder
1 % -100 = 1:
___0_____
-100 | 1
0
______
1 <--- remainder
