从键盘输入年、月、日。在屏幕输出此日期是该年的第几天。
源程序：
#include<stdio.h> int Leap(int year) //判断输入年份是否为闰年{ if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) { return 1; } else { return 0; }} int number(int year, int month, int day){ int sum = 0; int a[12] = { 31, 29, 31, 30.31, 30, 31, 31, 30, 31, 30, 31}; //闰年每月的天数 int b[12] = { 31, 28, 31, 30.31, 30, 31, 31, 30, 31, 30, 31}; //平年每月对应的天数 switch (Leap(year)) { case 1: for (int i = 0; i < month - 1; i++) { sum += a[i]; } break; case 0: for (int i = 0; i < month - 1; i++) { sum += b[i]; } break; } sum += day; return sum;}int main(){ int year, month, day; int sum = 0; printf("请输入一个日期：n"); scanf("%d%d%d", &year, &month, &day); sum = number(year, month, day); printf("n"); printf("该日期为%-4d年第%-3d天n", year, sum); return 0;}