C语言switch语句 #

switch (表达式) {
    case 常量1:
        语句1;
        break;
    case 常量2:
        语句2;
        break;
    default:
        语句3;
}

#include <stdio.h>

int main() {
    int day = 3;
    
    switch (day) {
        case 1:
            printf("星期一\n");
            break;
        case 2:
            printf("星期二\n");
            break;
        case 3:
            printf("星期三\n");
            break;
        case 4:
            printf("星期四\n");
            break;
        case 5:
            printf("星期五\n");
            break;
        case 6:
            printf("星期六\n");
            break;
        case 7:
            printf("星期日\n");
            break;
        default:
            printf("无效日期\n");
    }
    return 0;
}

#include <stdio.h>

int main() {
    int day = 1;
    
    switch (day) {
        case 1:
            printf("星期一\n");
        case 2:
            printf("星期二\n");
        case 3:
            printf("星期三\n");
        default:
            printf("其他\n");
    }
    return 0;
}

星期一
星期二
星期三
其他

#include <stdio.h>

int main() {
    int month = 2;
    
    switch (month) {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            printf("31天\n");
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            printf("30天\n");
            break;
        case 2:
            printf("28或29天\n");
            break;
        default:
            printf("无效月份\n");
    }
    return 0;
}

#include <stdio.h>

int main() {
    char grade = 'B';
    
    switch (grade) {
        case 'A':
            printf("优秀\n");
            break;
        case 'B':
            printf("良好\n");
            break;
        case 'C':
            printf("及格\n");
            break;
        default:
            printf("其他等级\n");
    }
    return 0;
}