求一个数的n次方

求一个数的n次方：

#include <stdio.h>
double pow (double x, int n)
{
    int i;
    double sum;
    sum=1;
    for (i=0; i<n; i++)
    {
        sum=sum*x;
    }
    return sum;
}
int main()
{
    double num;
    int n;
    scanf("%lf%d", &num, &n);
    printf("%.2lf\n", pow(num, n));
    return 0;
}