x的n次方

http://stevenkobes.com/ctest.html
#include<stdio.h>
#include<stdlib.h>

int foo(int x,int n)
{
    int val=1;
    if(n>0){
        if(n%2 == 1){
            val *= x;
        }
        val *= foo(x*x,n/2);
    }
    return val;
}

int main()
{
    printf("%d/n",foo(5,5));
    return 0;
}
foo函数实现计算x的n次方