计算x的y次方的值

#include<stdio.h>double fun(int x,int y){  int i=1;  double z=1;  for(i=1;i<=y;i++)     z=z*x;  return z;}int main(){  double fun(int x,int y);  double z;  int x,y;    printf("please input x y:");  scanf("%d %d",&x,&y);    z=fun(x,y);  printf("z=%.1f\n",z);  return 0;}