C++编程入门题目--No.4

题目：
输入某年某月某日，判断这一天是这一年的第几天？
程序分析：
以3月5日为例，应该先把前两个月的加起来，然后再加上5天即本年的第几天，特殊情况，闰年且输入月份大于3时需考虑多加一天。

#include <bits/stdc++.h>
using namespace std;
int main()
{
    int day, month, year, sum, leap;
    printf("
please input year,month,day
");
    scanf("%d,%d,%d", &year, &month, &day);
    switch (month) /*先计算某月以前月份的总天数*/
    {
    case 1:
        sum = 0;
        break;
    case 2:
        sum = 31;
        break;
    case 3:
        sum = 59;
        break;
    case 4:
        sum = 90;
        break;
    case 5:
        sum = 120;
        break;
    case 6:
        sum = 151;
        break;
    case 7:
        sum = 181;
        break;
    case 8:
        sum = 212;
        break;
    case 9:
        sum = 243;
        break;
    case 10:
        sum = 273;
        break;
    case 11:
        sum = 304;
        break;
    case 12:
        sum = 334;
        break;
    default:
        printf("data error");
        break;
    }
    sum = sum + day;                                           /*再加上某天的天数*/
    if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) /*判断是不是闰年*/
        leap = 1;
    else
        leap = 0;
    if (leap == 1 && month > 2) /*如果是闰年且月份大于2,总天数应该加一天*/
        sum++;
    printf("It is the %dth day.", sum);
}