c语言程序100例第4题 参考了参考答案

题目：输入某年某月某日，判断这一天是这一年的第几天？
1.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

#define _CRT_SECURE_NO_WARNINGS

#include <stdlib.h>
#include <stdio.h>


int main(){

		int day, month, year, sum, leap;
		printf("\nplease input year,month,day\n");
		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);
		system("pause");

}