编程实现统计某年某月份的天数。 例如：输入：2017.7 输出：31天

//输入一个月份，计算这个月份的天数#include<stdio.h>int main(){    int year,mon;    int leap;    int days;    printf("输入年份、月份：\n");    scanf("%d %d",&year,&mon);    fun(year);    switch(mon)    {        case 1:    days = 31;    break;    case 2:    if(leap == 1)    days = 28;    else    days = 29;    break;    case 3:    days = 31;    break;    case 4:    days = 30;    break;    case 5:    days = 31;    break;    case 6:    days = 30;    break;    case 7:    days = 31;    break;    case 8:    days = 31;    break;    case 9:    days = 30;    break;    case 10:    days = 31;    break;    case 11:    days =30;    break;    case 12:    days = 31;    break;            default:    printf("你来自火星！\n");    break;    }    printf("%d\n",days);    return 0;}fun (int year)     //用来判断输入的年份是闰年还是非闰年；{    int flag = 0; //不是闰年；    int leap;    if(year % 4 == 0)    {        if(year % 100)    {        if(year % 400 == 0)        {            flag =1;        }    }    else    {        flag = 1;           }    }    else    {        flag = 0;    }    if(flag == 1)    {        leap = 1;    }    else    {        leap = 0;    }}