程序代码：

#include <stdio.h>

#define Max_student 3 /*学生个数*/
#define Max_object 3  /*科目*/
int main(void){
  int mark[Max_student][Max_object];
  int i,j;
  printf("请输入%d个数字:\n",Max_student,Max_object);
  for(i=0;i<Max_student;i++)
    for(j=0;j<Max_object;j++)
      scanf("%d",&mark[i][j]);
  for(j=0;j<Max_object;j++){
    int s=0;
    for(i=0;i<Max_student;i++){
      s+=mark[i][j];
    }
    printf("第%d科的平均数:%f.\n",j+1,1.0*s/Max_student);
  }
  getch();
  return 0;
}