How do you do exponentiation in C?

Question

I tried \"x = y ** e\", but that didn\'t work.

Answer 1

int power(int x,int y){
 int r=1;
 do{
  r*=r;
  if(y%2)
   r*=x;
 }while(y>>=1);
 return r;
};

(iterative)

int power(int x,int y){
 return y?(y%2?x:1)*power(x*x,y>>1):1;
};

(if it has to be recursive)

imo, the algorithm should definitely be O(logn)