计算从出生到如今共生存了多少天

import java.util.Scanner;

public class Demo04 {
    public static void main(String[] args) {
        /*
        * 计算从出生到现在过了多少天
        * 1、出生那天，还有那年结束的几个月时间
        * 2、出生第二年之后，到今年之前的所有整年
        * 3、今年从年初到到这个月之前
        * 4、这个月过了多少天   这四个部分相加
        * */

        Scanner sc = new Scanner(System.in);//输入出生年月日
        System.out.println("请输入出生的年份");
        int startYear = sc.nextInt();
        System.out.println("请输入月份");
        int startMonth = sc.nextInt();
        System.out.println("请输入出生的那天");
        int startDay = sc.nextInt();
        //输入如今的年月日
        System.out.println("请输入今年的年份");
        int nowYear = sc.nextInt();
        System.out.println("请输入现在是几月");
        int nowMonth = sc.nextInt();
        System.out.println("请输入今天是几号");
        int nowDay = sc.nextInt();
        //First
        int first = 0;
        for(int a = startDay;a <= 12;a++){
            switch (a){
                case 1: case 3: case 5: case 7: case 8: case 10: case 12:
                    first += 31;
                    break;
                case 4: case 6: case 9: case 11:
                    first += 30;
                    break;
                    default:
                        if (startYear % 400 == 0|| (startYear % 4 == 0&& startYear % 100 != 0)){
                            first += 29;
                        }else{
                            first += 28;
                        }
                        first -= startDay;
            }
        }

        //Second
        int second = 0;
        for (int b = startYear + 1;b <= nowYear - 1;b++){
                if (b % 400 == 0|| (b % 4 == 0 && b % 100 != 0)){
                        second += 366;
                }else{
                        second += 365;
            }
        }
        //Third
        int third = 0;
        for (int c = 1; c <= nowMonth - 1;c++){
            switch (c){
                case 1: case 3: case 5: case 7: case 8: case 10: case 12:
                    third += 31;
                    break;
                case 4: case 6: case 9: case 11:
                    third += 30;
                    break;
                default:
                    if (nowDay % 400 == 0|| (nowDay % 4 == 0&& nowDay % 100 != 0)){
                        third += 29;
                    }else{
                        third += 28;
                    }
            }
        }

        int total = first + second + third + nowDay;
        System.out.println(total);



    }
}

原文地址：https://www.cnblogs.com/q2001/p/16406464.html