Shell中case...in分支语句的应用

case $变量 in
     选项1)
         分支1
         ;;
     选项2)
         分支1
         ;;
     选项3)
         分支1
         ;;
         .
         .
         .
     选项n)
         分支n
         ;;
     *)
         其它
         ;;
esac   

#include<stdio.h>
int main(int argc, const char *argv[])
{
   int year, month;
   printf("请输入年份和月份 > ");
   scanf("%d%d", &year, &month);
   if (year < 0) {
      puts("输入的年份错误");
      return -1;
   }
   if (month < 1 || month > 12) {
      puts("输入的月份错误");
      return -2;
   }
/*   
//思路1：
   if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0))
  {
    switch(month){
     case 1:
     case 3:
     case 5:
     case 7:
     case 8:
     case 10:
     case 12:
		printf("%d年%d月份，共计31天\n", year, month); 
		break;
     case 2:
        printf("%d年%d月份，共计29天\n", year, month);
		break;
		case 4:
		case 6:
		case 9:
		case 11:
        printf("%d年%d月份，共计30天\n", year, month);
		break;
		default:
		  printf("输入月份不合理\n");
		  break;
	 }
	} else {
     switch(month){
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
		  printf("%d年%d月份，共计31天\n", year, month); 
		  break;
        case 2:
          printf("%d年%d月份，共计28天\n", year, month);
		  break;
		case 4:
		case 6:
		case 9:
		case 11:
          printf("%d年%d月份，共计30天\n", year, month); 
		  break;
		default:
		  printf("输入月份不合理\n");
		  break;
	}
   }
*/  
 //思路2：
     switch(month){
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
		  printf("%d年%d月份，共计31天\n", year, month); 
		  break;
        case 2:
             if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0))
			 {
				 printf("%d年%d月份，共计29天\n", year, month);
			 } else {
				 printf("%d年%d月份，共计28天\n", year, month);
			 }
		  break;
		case 4:
		case 6:
		case 9:
		case 11:
          printf("%d年%d月份，共计30天\n", year, month); 
		  break;
		default:
		  printf("输入月份不合理\n");
		  break;
     }
   return 0;    
}

#!/bin/bash
read  -p "请输入查询的年份>>" Y
read  -p "请输入查询的月份>>" M
if [ $Y -lt 0 ]
then
	echo "输入的年份有误，请重新输入！！！"
	exit
fi
if [ $M -lt 1 -o $M -gt 12 ]
then
	echo "输入的月份有误，请重新输入！！！"
	exit
fi
case $M in
    4)
    echo "$Y年$M月共有30天"
	;;
    6)
    echo "$Y年$M月共有30天"
	;;
    9)
    echo "$Y年$M月共有30天"
	;;
    11)
    echo "$Y年$M月共有30天"
	;;
     2)
		 if [ $((Y%4)) -eq 0 -a $((Y%100)) -ne 0 ] || [ $((Y%400)) -eq 0 ]
		 then
           echo "$Y年$M月共有29天"
		 else
           echo "$Y年$M月共有28天"
		 fi
    ;;
    *)
    echo "$Y年$M月共有31天"
	;;
esac