输入某年某月某日，判断这一天是这一年的第几天。

#include<iostream>

using namespace std;

int main()

{

int year = 0, month = 0, day = 0,sum=0;

int fer;

cout << "请输入年份：";

cin >> year;

cout << "请输入月份：";

cin >> month;

cout << "请输入日期：";

cin >> day;

sum = day;

if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)

{

fer = 29;

}

else

fer = 28;

if (month>=1 && month<=12 && day>0 && day < 32)

{

switch (month - 1)

{

case 11: sum += 30;

case 10: sum += 31;

case 9: sum += 30;

case 8: sum += 31;

case 7: sum += 31;

case 6: sum += 30;

case 5: sum += 31;

case 4: sum += 30;

case 3: sum += 31;

case 2: sum += fer;

case 1: sum += 31;

}

cout << year << "年" << month << "月" << day << "日" << "是这一年的第" << sum << "天！";

cout << " " << endl;

}

else

{

cout << "请输入正确的日期！！";

cout << " " << endl;

}

system("pause");

return 0;

}