4 8关于#c++#的问题：用switch语句实现

Question

已知2009年1月1号是星期四，给定2009年的任何一天（月日），求这天是星期几（输出最后结果要求用switch语句实现）。一周七天用以下标识：
Monday，Tuesday，Wednesday，Thursday，Friday，Saturday，Sunday
例如：输入 3.30 时应输出 Monday，输入 6.19 时应输出 Friday

Answer 1

#include<stdio.h>
#include<conio.h>
int main(){
    int i,judge,sum=0;
    int month;
    float date,day;
    printf("please input a date in 2009\n");
    scanf("%f",&date);
    month=(int)date;
    day=(date-month)*100;
    if(month==1)
        sum=day;
    else{
        for(i=1;i<month;i++)
            switch(i){
                case 1:
                case 3:
                case 5:
                case 7:
                case 8:
                case 10:
                case 12:
                sum+=31;
                break;
                case 2:
                sum+=28;
                break;
                case 4:
                case 6:
                case 9:
                case 11:
                sum+=30;
                break;
                default:
                break;
            }
        sum+=day;
    }
    judge=(sum-1)%7+4;
    switch(judge){
        case 8:
        printf("Monday\n");
        break;
        case 9:
        printf("Tuesday\n");
        break;
        case 10:
        printf("Wednesday\n");
        break;
        case 4:
        printf("Thursday\n");
        break;
        case 5:
        printf("Friday\n");
        break;
        case 6:
        printf("Saturday\n");
        break;
        case 7:
        printf("Sunday\n");
        break;
        default:
        break;
    }
    return 0;
}