How do you do *integer* exponentiation in C#?

Question

The built-in Math.Pow() function in .NET raises a double base to a double exponent and returns a double result.

What's the best way to do the same with integers?

Added: It seems that one can just cast Math.Pow() result to (int), but will this always produce the correct number and no rounding errors?

Answer 1

A pretty fast one might be something like this:

int IntPow(int x, uint pow) {     int ret = 1;     while ( pow != 0 )     {         if ( (pow & 1) == 1 )             ret *= x;         x *= x;         pow >>= 1;     }     return ret; } 

Note that this does not allow negative powers. I'll leave that as an exercise to you. :)

Added: Oh yes, almost forgot - also add overflow/underflow checking, or you might be in for a few nasty surprises down the road.

Answer 2

LINQ anyone?

public static int Pow(this int bas, int exp) {     return Enumerable           .Repeat(bas, exp)           .Aggregate(1, (a, b) => a * b); } 

usage as extension:

var threeToThePowerOfNine = 3.Pow(9);