#include <stdio.h>
#include<string.h>
#include <stdlib.h>
int stu_ID[3]={1001,1002,1003};
int stu_class[3]={11,22,11};
float stu_score [3][3]={{99.5,88.5,89.5},{77.9,56.5,87.5},{92.5,99.0,60.5}};
char stu_name[3][10]={"zhang","li","wang"};
float stu_sum[3];

int main()
{
    int i,j;
    void add(float b[3][3]);
    void sort(float a[3]);
    void exchange(int,int);
    void swap(int,int);

    add(stu_score);
    sort(stu_sum);

    for(i=0;i<3;i++)
    {printf("%d,%d,%s,",stu_ID[i],stu_class[i],stu_name[i]);
          for(j=0;j<3;j++)
            {printf("%3.1f,",stu_score[i][j]); }
    printf("%4.1f\n",stu_sum[i]);
    }
return  0;
}

void add(float b[3][3])
  {   int i,j;
      float stu_sum[3]={0};
      for(i=0;i<3;i++)
        for(j=0;j<3;j++)
          {stu_sum[i]+=b[i][j];}
  }

void  sort(float a[3])
  {
  int i,j;
  for(i=0;i<2;i++)
    for(j=0;j<2-i;j++)
  {
      if(a[j]<a[j+1])
       {
        exchange(j,j+1);
        swap(j,j+1);
       }
  }

  }
void exchange(int i,int j)
{
    int t;
    float temp;
    t=stu_class[i];stu_class[i]=stu_class[j];stu_class[j]=t;
    t=stu_ID[i];stu_ID[i]=stu_ID[j];stu_ID[j]=t;
    for(t=0;t<3;t++)
    {temp=stu_score[i][t];stu_score[i][t]=stu_score[j][t];stu_score[j][t]=temp;}
}
void swap(int i,int j)
{
    char n[10];
    strcpy(n,stu_name[i]);strcpy(stu_name[i],stu_name[i+1]);strcpy(stu_name[i+1],n);
}

error: incompatible implicit declaration of function "excchange"
error:incompatible implicit declaration of function "swap"

code block 提醒的错误。

按照指示改后，虽然没有提醒错误，然而程序根本就没有运行，直接跳过函数操作输出了。数据都没有变化，为什么，求解

谢谢，去掉后果然对了