枚举 与 枚举的应用

# include <stdio.h>

//只定义了一个数据类型，并没有定义变量， 该数据类型的名字是 enum WeekDay , 默认 值是用0开始
// MonDay = 0 , TuesDay = 1 .... , SunDay = 6
enum WeekDay
{
    MonDay, TuesDay, WednesDay, ThursDay, FriDay, SaturDay, SunDay
};

int main(void)
{
    //int day; //day定义成int类型不合适
    enum WeekDay day = SunDay;
    printf("%d\n", day);

    return 0;
}

# include <stdio.h>

//只定义了一个数据类型，并没有定义变量， 该数据类型的名字是 enum WeekDay , 值是用A的ASC2码开始
// MonDay = 65 , TuesDay = 66 ....  
enum WeekDay
{
    MonDay = ‘A‘, TuesDay, WednesDay, ThursDay, FriDay, SaturDay, SunDay
};

int main(void)
{
    //int day; //day定义成int类型不合适
    enum WeekDay day = SunDay;
    printf("%d\n", day);

    return 0;
}

/*
    对枚举的应用!
*/
# include <stdio.h>

enum weekday
{
    MonDay, TuesDay, WednesDay, ThursDay, FriDay, SaturDay, SunDay //考虑将WednesDay改为WednesDay = 5之后，MonDay与SunDay的值是多少？
};

void f(enum weekday i) //本函数的目的只是期望接受0～6之间的数字，将形参i定义为枚举型，可以有效的避免传参失误的问题
{
    switch (i)
    {
    case 0:
        printf("MonDay!\n");
        break;
    case 1:
        printf("TuesDay!\n");
        break;
    case 2:
        printf("WednesDay!\n");
        break;
    case 3:
        printf("ThursDay!\n");
        break;
    case 4:
        printf("FriDay!\n");
        break;
    case 5:
        printf("SaturDay!\n");
        break;
    case 6:
        printf("SunDay!\n");
        break;  
    }          
}

int main(void)
{
    f(FriDay); //虽然FriDay本质上就是5，但直接写成f(5);就是错的， 也不能写成f(10); 考虑为什么！ 嘿嘿

    return 0;
}