共同体类型，学生，教师

#include<stdio.h>
struct                                                                     //声明无名结构体类型
{
 int num;                                                               //编名
 char name[10];                                                         //姓名
 char sex;                                                              //性别
 char job;                                                              //职业
 union                                                                  //声明无名共同体类型
 {
  int clas;                                                          //班级
  char position[10];                                                 //职务
 }category;                                                              //共同体变量
}person[2];                                                                 //定义结构体数组，有两个元素
int main()
{
 int i;
 for(i=0;i<2;i++)
 {
  printf("please enter the data of person:\n");
  scanf("%d %s %c %c",&person[i].num,&person[i].name,&person[i].sex,&person[i].job);       //输入编号，姓名，性别，职业
  if(person[i].job=='s')                                                                    //学生
   scanf("%d",&person[i].category.clas);                                                  //输入班级
  else
   if(person[i].job=='t')                                                                 //教师
    scanf("%s",person[i].category.position);                                            //输入职务
   else
    printf("input error!");
 }
 printf("\n");
 printf("No.  name  sex job class/position\n");
 for(i=0;i<2;i++)
 {
  if(person[i].job=='s')
   printf("%-6d%-6s%\-4c%-4c%-10d\n",person[i].num,person[i].name,person[i].sex,person[i].job,person[i].category.clas);
  else
   printf("%-6d%-6s%\-4c%-4c%-10s\n",person[i].num,person[i].name,person[i].sex,person[i].job,person[i].category.position);
 }
 return 0;
}