输入年份和月份，输出这一年的这一月有多少天。需要考虑闰年。

#include<stdio.h>
int main()
{
    int m,y,days;
    scanf("%d %d",&y,&m);
    switch(m)
    {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12: days=31;break;
        case 4:
        case 6:
        case 9:
        case 11: days=30;break;
    }
    if(((y%100 !=0 && y%4 == 0) || y%400 == 0))//闰年
    {
        if(m==2)
        {
            days=29;
            printf("%d\n",days);
        }
        else
            printf("%d\n",days);
    }
    else//不是闰年
    {
        if(m==2)
        {
            days=28;
            printf("%d\n",days);
        }
        else
            printf("%d\n",days);
    }
}

list1 = ['小寒，大寒', '立春，雨水','惊蛰，春分','清明，谷雨','立夏，小满','夏至,芒种','小暑、大暑','立秋、处暑','白露、秋分','寒露、霜降','立冬、小雪','大雪、冬至']
list2 = [1, 2, 3, 4, 5,6,7,8,9,10,11,12]
day_month = [31, 59, 90, 120, 151,181,212,243,273,304,334,365]
list3 = [1, 2, 3, 4, 5,6,7,8,9,10,11,12]
y=0
m=0
d=0
c=365
y=(int(input("年份")))
m=(int(input("月份")))
d=(int(input("天")))
if y%4==0:
    if y%100==0:
        print("是闰年")
        day_month[1] = 29
        c=366
    else:
        print("是平年")
else:
    print("是平年")
if m==1:
    print(list1[1],d,"天")
elif m==2:
    print(list1[2],d+day_month[1],"天",d+day_month[1]/c)
elif m==3:
    print(list1[3],d + day_month[3],"天")
elif m==4:
    print(list1[4],d + day_month[4],"天")
elif m==5:
    print(list1[5],d + day_month[5],"天")
elif m==6:
    print(list1[6],d + day_month[6],"天")
elif m==7:
    print(list1[7],d + day_month[7],"天")
elif m==8:
    print(list1[8],d + day_month[8],"天")
elif m == 9:
    print(list1[9],d + day_month[9],"天")
elif m == 10:
    print(list1[10],d + day_month[10],"天")
elif m==11:
    print(list1[11],d + day_month[11],"天")
elif m==12:
    print(list1[12],d + day_month[12],"天")
else:
    print("error")

function mGetDate(year, month) {
    var d = new Date(year, month, 0);
    return d.getDate();
}


function getFormatYear() {
    let date = new Date()
    const year = date.getFullYear() // 获取当前年份
    // 每年12个月 这是固定的
    const list = Array.from({
        length: 12
    }, (item, index) => {
        let month = index + 1
        month = month.padStart(2, '0')
        return {
            value: month,
            label: `${month}月`,
            children: Array.from({
                length: mGetDate(year, month, 0)
            }, (m, mIndex) => {
                let day = mIndex + 1
                day = day.padStart(2, '0')
                return {
                    value: day,
                    label: `${day}日`
                }
            })
        }
    })
    return list
}
getFormatYear()