Efficient implementation of Power(x,y)

 
int power (a, b)
{
    int result = 1;
    while (b--)
        result = result * a;
    return result;
}

1. 'b' can be expressed as 2^l + 2^m + 2ⁿ ...
   
   Example:
   a¹⁰ = a⁸⁺²
   = a⁸ * a²
   
   
   
2. Also note that multiplying a number by itself doubles the power.
   Example: a*a = a²
   and a⁴ * a⁴ = a⁸
   

int power (int a, int b)
{
    int result = 1;
    while (b != 0)
    {
        if ((b&1) != 0)
            result *= a;
        b = b>>1;
        a = a*a; // Imp: self multiplication doubles the power of 'a'
    }
    return result;
}

power (1, 3) = 1
power (3, 4) = 81
power (2, 5) = 32
power (5, 5) = 3125
power (7, 3) = 343
power (10, 4) = 10000