switch/case语句一例

#include <stdio.h>
 int main(void)
{int y,m,n,d;
n=0;
 printf("input your year\n");
 scanf("%d%d%d",&y,&m,&d);// 格式是2010 02 02这样默认是空格分开

 switch(m){
 case 12: n+=30;
 case 11: n+=31;
 case 10: n+=30;
 case 9: n+=31;
 case 8: n+=31;
 case 7: n+=30;
 case 6: n+=31;
 case 5: n+=30;
 case 4: n+=31;
 case 3: if((y%4==0&&y%100!=0)||y%400==0) n+=29;else n+=28;
 case 2:n+=31;
 case 1: n+=d;printf("today is %d of %d\n",n,y);break;
 default: printf("please input a valid year no.\n");}
}

仔细体会下case 里不带break的用法，假如用break，那2月要d+31以此类推了。

最后说下这个2010 02 31也能算出结果，健壮性不够，要做判断，用数组可能更好点。