#include <iostream>
using namespace std;
//IsLeap函数判断一个年份是否为闰年，方法如下:
bool IsLeap(int year)
{
   return (year % 4 ==0 || year % 400 ==0) && (year % 100 !=0);
}

//上面的StringToDate函数用于取出日期中的年月日并判断日期是否合法
//从字符中最得年月日 规定日期的格式是yyyy-mm-dd
bool StringToDate(string date, int& year, int& month, int& day)
{
	year = atoi((date.substr(0,4)).c_str());
	month = atoi((date.substr(5,2)).c_str());
	day = atoi((date.substr(8,2)).c_str());
	int DAY[12]={31,28,31,30,31,30,31,31,30,31,30,31};
	if(IsLeap(year)){
	     DAY[1] = 29;
	}
	return year >= 0 && month<=12 && month>0 && day<=DAY[month] && day>0;
}

//DayInYear能根据给定的日期，求出它在该年的第几天，代码如下
int DayInYear(int year, int month, int day)
{
	//int _day = 0;
    int DAY[12]={31,28,31,30,31,30,31,31,30,31,30,31};
	if(IsLeap(year))
		DAY[1] = 29;
	for(int i=0; i<month - 1; ++i)
	{
	    day += DAY[i];
	}
	return day;
}

int DaysBetween2Date(string date1, string date2)
{
     //取出日期中的年月日
	 int year1, month1, day1;
	 int year2, month2, day2;
	 if(!StringToDate(date1, year1, month1, day1) || !StringToDate(date2, year2,month2,day2))
	 {
	    cout<<"输入的日期格式不正确";
		return -1;
	 }
	 if(year1 == year2 && month1 == month2)
	 {
	      return day1 > day2 ? day1 - day2 : day2 - day1;
	 
	 //如果年相同
	 }else if(year1 == year2)
	 {
	     int d1, d2;
		 d1 = DayInYear(year1, month1, day1);
		 d2 = DayInYear(year2, month2, day2);
		 return d1 > d2 ? d1 - d2 : d2 - d1;
	 
	 //年月都不相同
	 }else{
	     //确保year1年份比year2早
		 if(year1 > year2)
		 {
			 //swap进行两个值的交换
		     swap(year1, year2);
			 swap(month1, month2);
			 swap(day1, day2);
		 }
		 int d1,d2,d3;
		 if(IsLeap(year1))
			 d1 = 366 - DayInYear(year1,month1, day1); //取得这个日期在该年还于下多少天
		 else
			 d1 = 365 - DayInYear(year1,month1, day1);
         d2 = DayInYear(year2,month2,day2); //取得在当年中的第几天
		 cout<<"d1:"<<d1<<", d2:"<<d2;
		 
		 d3 = 0;
		 for(int year = year1 + 1; year < year2; year++)
		 {
		     if(IsLeap(year))
				 d3 += 366;
			 else
				 d3 += 365;
		 }
		 return d1 + d2 + d3;
	 }
}
int main()
{
	int a = DaysBetween2Date("2010-11-11","2011-11-11");
	cout<<"2010-11-11到2011-11-11相差 "<<a<<" 天";
    system("pause");
	return 0;
}