switch (整型表达式)
{
  语句项;
}

//由一些case语句组成,如:
case 整型常量表达式:
  语句;

#include<stdio.h>
int main()
{
  int day = 0;
  scanf("%d", &day);
  if (1 == day)
    printf("星期1\n");
  else if (2 == day)
    printf("星期2\n");
  else if (3 == day)
    printf("星期3\n");
  else if (4 == day)
    printf("星期4\n");
  else if (5 == day)
    printf("星期5\n");
  else if (6 == day)
    printf("星期6\n");
  else if (7 == day)
    printf("星期天\n");
  else
    printf("输入错误\n");
  return 0;
}

#include<stdio.h>
int main()
{
  int day = 0;
  scanf("%d", &day);
  switch (day)
  {
  case 1:
    printf("星期一\n");
    break;
  case 2:
    printf("星期二\n");
    break;
  case 3:
    printf("星期三\n");
    break;
  case 4:
    printf("星期四\n");
    break;
  case 5:
    printf("星期五\n");
    break;
  case 6:
    printf("星期六\n");
    break;
  case 7:
    printf("星期日\n");
    break;
  }
  return 0;
}

switch(常量)
{
    case 常量1:
        printf(" ");
        break;
    case 常量2:
        printf(" ");
        break;
}

switch(常量)
{
    case 常量1:
    case 常量2:
        printf(" ");
        break;
    case 常量3:
        printf(" ");
}

witch(常量)
{
    defult:
        printf("输入错误");
        break
    case 常量1:
    case 常量2:
        printf(" ");
        break;
    case 常量3:
        printf(" ");
        break;        
}

#include<stdio.h>
int main()
{
  int day = 0;
  scanf("%d", &day);
  switch (day)
  {
  case 1:
  case 2:
  case 3:
  case 4:
  case 5:
    printf("weekday\n");
    break;
  case 6:
  case 7:
    printf("weekend\n");
    break;
  default:
    printf("输入错误\n");
    break;
  }
  return 0;
}

#include <stdio.h>
int main()
{
  int n = 1;
  int m = 2;
  switch (n)
  {
  case 1:
    m++;
  case 2:
    n++;
  case 3:
    switch (n)//switch允许嵌套使用
    {
    case 1:
      n++;
    case 2:
      m++;
      n++;
      break;
    }
  case 4:
    m++;
    break;
  default:
    break;
  }
  printf("m = %d, n = %d\n", m, n);
  return 0;
}