text: // 使用枚举类型
  // 打印一个月中的每一天的程序
  #include <stdio.h>
  
  int main(void){
  	enum month {january = 1, february, march, april, may, june,
  		july, august, september, october, novermber, december };
  	enum month aMonth;
  	int days;
  	printf("Enter month number: ");
  	scanf("%i", &aMonth);
  	switch(aMonth){
  		case january:
  		case march:
  		case may:
  		case july:
  		case august:
  		case october:
  		case december:
  			days = 31;
  			break;
  		case april:
  		case june:
  		case september:
  		case novermber:
  			days = 30;
  			break;
  		case february:
  			days = 28;
  			break;
  		default:
  			printf("bad month numbe\n");
  			days = 0;
  			break;
  	}
  	if(days != 0)
  		printf("Number of days is %i\n", days);
  	if(aMonth == february)
  		printf("...or 29 if it's a leap year\n");
  	return 0;
  }
  