#include<stdio.h>
#include<stdlib.h>
enum WeekDay{
　　Monday,Tuesday,Wednesday,Thursday,Friday,Saturday,Sunday
};
main(){
　　//枚举，规定变量取值范围只能从预先定义好的值中选择
　　enum WeekDay day = Sunday;
　　printf("%d\n",day);
}

C之枚举