Calculating powers of integers

Question

Is there any other way in Java to calculate a power of an integer?

I use Math.pow(a, b) now, but it returns a double, and that is usually a

Answer 1

A simple (no checks for overflow or for validity of arguments) implementation for the repeated-squaring algorithm for computing the power:

/** Compute a**p, assume result fits in a 32-bit signed integer */ 
int pow(int a, int p)
{
    int res = 1;
    int i1 = 31 - Integer.numberOfLeadingZeros(p); // highest bit index
    for (int i = i1; i >= 0; --i) {
        res *= res;
        if ((p & (1< 0)
            res *= a;
    }
    return res;
}

The time complexity is logarithmic to exponent p (i.e. linear to the number of bits required to represent p).