2．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国年且输入月份大于了时需考虑多加一天。#include=stdiohint main int daymonth yearsum leap;printfInplease input yearmonthdayn;scanfddd_switchmonth先计算某月以前月

#include <stdio.h>

int main() { int day, month, year, sum, leap; printf("Please input year, month, day: "); scanf("%d,%d,%d", &year, &month, &day); switch (month) { case 1: sum = day; break; case 2: sum = 31 + day; break; case 3: sum = 59 + day; break; case 4: sum = 90 + day; break; case 5: sum = 120 + day; break; case 6: sum = 151 + day; break; case 7: sum = 181 + day; break; case 8: sum = 212 + day; break; case 9: sum = 243 + day; break; case 10: sum = 273 + day; break; case 11: sum = 304 + day; break; case 12: sum = 334 + day; break; default: printf("Data error\n"); return 0; } if ((year % 400 == 0) || (year % 4 == 0 && year % 100 != 0)) { leap = 1; } else { leap = 0; } if (leap == 1 && month > 2) { sum++; } printf("It is the %dth day. In %d\n", sum, year); return 0; }