【程序14】

题目：输入某年某月某日，判断这一天是这一年的第几天？

import java.util.*;

public class lianxi14 {

    public static void main(String[] args) {

        int year, month, day;

        int days = 0;

        int d = 0;

        int e;

        input fymd = new input();

        do {

             e = 0;

             System.out.print("输入年：");

             year =fymd.input();

             System.out.print("输入月：");

             month = fymd.input();

             System.out.print("输入天：");

             day = fymd.input();

             if (year < 0 || month < 0 || month > 12 || day < 0 || day > 31) {

             System.out.println("输入错误，请重新输入！");

             e=1 ; 

             }

        }while( e==1);

        for (int i=1; i <month; i++) {

            switch (i) {

              case 1:

              case 3:

              case 5:

              case 7:

              case 8:

              case 10:

              case 12:

                days = 31;

                break;

              case 4:

              case 6:

              case 9:

              case 11:

                days = 30;

                break;

              case 2:

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

                    days = 29;

                } else {

                    days = 28;

                }

                break;

              }

            d += days;

        }

        System.out.println(year + "-" + month + "-" + day + "是这年的第" + (d+day) + "天。");

    }

}

class input{

    public int input() {

        int value = 0;

        Scanner s = new Scanner(System.in);

        value = s.nextInt();

        return value;

    }

}