VC++跑的程序 问一下各位大神这里出了什么问题

Question

#include<stdio.h>
#include<time.h>
#include<math.h>
clock_t start,stop;
double duration;
#define MAXN 10 /*多项式最大项数，即多项式阶数+1*/
double f1(int n,double a[],double x);
double f2(int n,double a[],double x);

int main()
{ int i;
  double a [MAXN];/*存储多项式的系数*/
  for(i=0;i<MAXN;i++)a[i]=(double)i;

  start=clock();
  f1(MAXN-1,a,1.1);
  stop=clock();
  duration=((double)(stop-start))/CLK_TCK;
  printf("ticks1=%f\n",(double)(stop-start));
  printf("duration1=%6.2e\n",duration);

  start=clock();
  f2(MAXN-1,a,1.1);
  stop=clock();
  duration=((double)(stop-start))/CLK_TCK;
  printf("ticks2=%f\n",(double)(stop-start));
  printf("duration2=%6.2e\n",duration);
  return 0;
}

以上为代码段

Answer 1

double f1(int n,double a[],double x);

double f2(int n,double a[],double x);

函数虽然有声明，但是没有实现方法体，实现方法体即可运行。