按月、按天计算失效日期的代码实现

【背景】：在我们计算截止日期、失效时期的时候，可能存在按年、按月、按天统计失效的情况。比如：当前日期是2014-12-22,900天后失效，失效日期是多少？17个月后失效，失效日期是多少。通过本文源码，你都可以得到答案。

为验证程序的正确性，本文对每个接口函数都做了大量的测试用例。

// sn_ctrl.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <assert.h>
#include <iostream>
using namespace std;

const int MAX_MONTH_CNTS_IN_YEAR = 12;

/*
**@brief:判定年份是否为闰年.
**@param: iYear当前年份.
**@return:true,闰年; false,平年.
*/
bool IsLeapYear(unsigned int iYear)
{
	if ( (iYear%4 == 0 && iYear%100 != 0) || (iYear%400 == 0) )
	{
		return true;
	}
	else
	{
		return false;
	}
}

/*
**@brief:判定某年某月的天数.
**@param: iYear当前年份，iMonth当前月份;
**@return:当前年、月的天数.
*/
unsigned int daysInMonth(unsigned int iYear, unsigned int iMonth)
{
	assert(iMonth >=1 && iMonth <= MAX_MONTH_CNTS_IN_YEAR);
	int iDaysInMonth = 0;
	switch(iMonth)
	{
		case 1:
		case 3:
		case 5:
		case 7:
		case 8:
		case 10:
		case 12:
			iDaysInMonth = 31;
		break;
		case 4:
		case 6:
		case 9:
		case 11:
			iDaysInMonth = 30;
		break;
		case 2:
			if (IsLeapYear(iYear))
			{
				iDaysInMonth = 29;
			}
			else
			{
				iDaysInMonth = 28;
			}
		break;
		default:
			cout << "Error Month!!" << endl;
			break;
	}
	return iDaysInMonth;
}


struct Date
{
	unsigned int date_year;
	unsigned int date_month;
	unsigned int date_day;
};

class DateOp
{
public:
	DateOp(){}
	DateOp(Date thisDate):theDate(thisDate){}
	virtual ~DateOp(){}
	Date DataAddmonths(Date date_init, unsigned int month_cnts);
	Date DateAddDays(Date date_init, unsigned int day_cnts);

private:
	Date theDate;
};

/*
**@brief:初始月份加几个月后的日期.
**@param: dateInit初始日期，iMonthCnts过几个月;
**@return:计算后的新的日期.
*/
Date DateOp::DataAddmonths(Date dateInit, unsigned int iMonthCnts)
{
	assert (iMonthCnts >= 1);
	Date dateAfterAdd = dateInit;

	unsigned int iMonthNewPos = dateInit.date_month + iMonthCnts;
	if (iMonthNewPos > MAX_MONTH_CNTS_IN_YEAR)  //求和后超过12
	{
		unsigned int iYearCnts = (iMonthNewPos)/(MAX_MONTH_CNTS_IN_YEAR);
		unsigned int iMonthNew = (iMonthNewPos)%(MAX_MONTH_CNTS_IN_YEAR);
		if (0 == iMonthNew) //月份为0特殊处理
		{
			dateAfterAdd.date_year = dateInit.date_year + iYearCnts -1;
			iMonthNew = 12;
		}
		else
		{
			dateAfterAdd.date_year = dateInit.date_year + iYearCnts;
		}	
		dateAfterAdd.date_month = iMonthNew;
	
	}
	else  //求和后不超过12
	{
		dateAfterAdd.date_year = dateInit.date_year;
		dateAfterAdd.date_month = dateInit.date_month + iMonthCnts;
	}

	//2月份特殊处理
	if ( (30 == dateInit.date_day || 31 == dateInit.date_day) && (2 == dateAfterAdd.date_month))
	{
		dateAfterAdd.date_day = daysInMonth(dateAfterAdd.date_year, dateAfterAdd.date_month);
	}
	//30天的月份特殊处理
	else if ((31 == dateInit.date_day) && ((4 == dateAfterAdd.date_month) || (6 == dateAfterAdd.date_month) ||
		     (9 == dateAfterAdd.date_month) || (11 == dateAfterAdd.date_month)))
	{
		dateAfterAdd.date_day = 30;
	}
	else
	{
		dateAfterAdd.date_day = dateInit.date_day;
	}
	return dateAfterAdd;
}

/*
**@brief:初始月份加*天后的日期.
**@param: dateInit初始日期，iMonthCnts过多少天;
**@return:计算后的新的日期.
*/
Date DateOp::DateAddDays(Date dateInit, unsigned int day_cnts)
{
	assert(day_cnts >= 1);
	cout << "+ " << day_cnts << endl;
	Date dateAfterAdd = dateInit;

	unsigned int iCurDaysInMonth = daysInMonth(dateInit.date_year, dateInit.date_month); //当前月的总天数.
	//cout << "iCurDaysInMonth = " << iCurDaysInMonth << endl;
	int iDayTotal = day_cnts;
	if (dateInit.date_day + day_cnts <= iCurDaysInMonth)
	{
		dateAfterAdd.date_day = dateInit.date_day + day_cnts;
		return dateAfterAdd;
	}

	int iLeftDaysInCurMonth = iCurDaysInMonth - dateInit.date_day; //当前月剩余天数.
	//cout << endl << "iDayTotal = " << iDayTotal << "\t iLeftDayInCurmonth = " << iLeftDaysInCurMonth << endl << endl;
	//cout << "iAvgMonthCnts = " << iAvgMonthCnts << endl << endl;

	unsigned int iDaysInMonth = 0;
	int iLeftDaysTotal = 0;  //统计大约几个月的实际总天数.
	unsigned int iMonthCnts = 0;
	while (iLeftDaysTotal <= iDayTotal - iLeftDaysInCurMonth)
	{
		++iMonthCnts;
		unsigned int iCurMonth = dateInit.date_month + iMonthCnts;
	// cout << "iCurMonth = " << iCurMonth << endl;
		unsigned int iYearCnts = 0;
		if (iCurMonth > 12)
		{
			iYearCnts = (iCurMonth)/(MAX_MONTH_CNTS_IN_YEAR);
		}
	
		//cout << "iYearCnts = " << iYearCnts << endl;

		if (0 == iYearCnts)
		{
			dateAfterAdd.date_year = dateInit.date_year;
			dateAfterAdd.date_month = iCurMonth;
			iDaysInMonth = daysInMonth(dateInit.date_year, iCurMonth);
			iLeftDaysTotal += iDaysInMonth;
		}
		else
		{
			unsigned int iMonthNew = (iCurMonth)%(MAX_MONTH_CNTS_IN_YEAR);
			if (0 == iMonthNew) //月份为0特殊处理
			{
				dateAfterAdd.date_year = dateInit.date_year + iYearCnts -1;
				iMonthNew = 12;
			}
			else
			{
				dateAfterAdd.date_year = dateInit.date_year + iYearCnts;
			}
			dateAfterAdd.date_month = iMonthNew;
			iDaysInMonth = daysInMonth(dateAfterAdd.date_year, iMonthNew);
			iLeftDaysTotal += iDaysInMonth;
			
		}//end else
		//对于超出的做特殊处理.
		if (iLeftDaysTotal > (iDayTotal - iLeftDaysInCurMonth))
		{
			iLeftDaysTotal -= iDaysInMonth;
			break;
		}
	}

	//cout << "iDayTotal  =" << iDayTotal << "\tiLeftDaysInCurMonth = " << iLeftDaysInCurMonth  //bug??
		//<< "\tiLeftDaysTotal = " << iLeftDaysTotal << endl;
	if (iDayTotal - iLeftDaysInCurMonth - iLeftDaysTotal < 0)
	{
		dateAfterAdd.date_day = iDayTotal - iLeftDaysInCurMonth;
	}
	else
	{
		dateAfterAdd.date_day = iDayTotal - iLeftDaysInCurMonth - iLeftDaysTotal;
	}
	
	if (dateAfterAdd.date_month > 12)
	{
		dateAfterAdd.date_year += 1;
		dateAfterAdd.date_month = 1;
	}
	if (dateAfterAdd.date_day == 0)
	{
		if (1 == dateAfterAdd.date_month)
		{
			dateAfterAdd.date_month = 12;
			dateAfterAdd.date_year -= 1;
		}
		else
		{
			dateAfterAdd.date_month -= 1;
		}

		dateAfterAdd.date_day = daysInMonth(dateAfterAdd.date_year, dateAfterAdd.date_month);
	}
	assert((dateAfterAdd.date_month >= 1) && (dateAfterAdd.date_month <= 12));
	assert((dateAfterAdd.date_day >= 1) && (dateAfterAdd.date_day <= 31));
	return dateAfterAdd;
}

/*
**@brief:打印日期格式.
**@param: theDate提供打印的日期
**@return:空.
*/
void DisplayDate(Date& theDate)
{
	cout << theDate.date_year << "/" << theDate.date_month 
		 << "/" << theDate.date_day << "\t";
	cout << endl << endl;
}


/*
**@brief:测试用例:测试某年是否为闰年.
**@param: 空.
**@return:空.
*/
void testLeapYearOrNot()
{
	unsigned int iBeginYear=1900;
	unsigned int iEndYear=3000;

	cout << "From " << iBeginYear << " To " << iEndYear << endl;

	for (unsigned int iYear = iBeginYear; iYear <= iEndYear; ++iYear)
	{
		if (IsLeapYear(iYear))
		{
			cout << iYear << "\t";
		}
	}
	cout << endl;
}


/*
**@brief:单元测试用例，某年某月有多少天.
**@param: 空.
**@return:空.
*/
void testDaysInMonth()
{
	unsigned int iBeginYear = 1980;
	unsigned int iEndYear = 2020;
	unsigned int iBeginMonth = 1;
	unsigned int iEndMonth = 12;
	unsigned int iDaysOfYear = 0;

	for (unsigned int iYear = iBeginYear; iYear <= iEndYear; ++iYear)
	{
	    iDaysOfYear = 0;
		cout << "Year:" << iYear << endl;
		for (unsigned int iMonth = iBeginMonth; iMonth <= iEndMonth; ++iMonth)
		{

			unsigned int iDaysInmonth = daysInMonth(iYear,iMonth);
			iDaysOfYear += iDaysInmonth;
			cout << iDaysInmonth << "\t";
		}

		cout << endl;
		cout << iYear << " has " << iDaysOfYear << " days!" << endl << endl;
	}
}

/*
**@brief:单元测试用例，测试几个月后日期.
**@param: 空.
**@return:空.
*/
void testDataAddmonths()
{
	unsigned int iBeginYear = 2014;
	unsigned int iEndYear = 2015;

	unsigned int iBeginMonths = 1;
	unsigned int iEndMonths = 30;

	Date beginDate;
	beginDate.date_year = 1980;
	beginDate.date_month = 1;
	beginDate.date_day = 31;
	Date endDate = beginDate;
	DateOp dateOp;

	for (unsigned int iYear = iBeginYear; iYear <= iEndYear; ++iYear)
	{
		beginDate.date_year = iYear;
		(void)DisplayDate(beginDate);
		cout << endl;
		for (unsigned int iMonth = 1; iMonth <= MAX_MONTH_CNTS_IN_YEAR; ++iMonth)
		{
			beginDate.date_month = iMonth;
			cout << iMonth << "\t";
			for (unsigned int iMonthCnts = iBeginMonths; iMonthCnts <= iEndMonths; ++iMonthCnts)
			{
				endDate = dateOp.DataAddmonths(beginDate, iMonthCnts);
				cout << " +" << iMonthCnts << " ";
				(void)DisplayDate(endDate);
			}//end for iMonthCnts;
			cout << endl << endl;
		}//end for iMonth
		cout << endl << endl << endl;
	}//end for iYear
}

/*
**@brief:单元测试用例，测试给定天后的日期.
**@param: 空.
**@return:空.
*/
void testDataAddDays()
{
	Date beginDate;
	beginDate.date_year = 1988;
	beginDate.date_month = 7;
	beginDate.date_day = 19;
	
	DateOp dateOp;
	cout << "Init Date is :" << endl;
	(void)DisplayDate(beginDate);

	Date endDate = beginDate;



	endDate = dateOp.DateAddDays(beginDate, 1); //1988-7-20
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 12); //1988-7-31
	(void)DisplayDate(endDate); 


	endDate = dateOp.DateAddDays(beginDate, 13); //1988-8-1
	(void)DisplayDate(endDate); 


	endDate = dateOp.DateAddDays(beginDate, 100); //1988-10-27
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 200); //1989-2-4
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 500); //1989-12-1
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 954); //1991-2-28
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 955); //1991-3-1
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 1000); //1991年4月15日星期一
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 2000); //1994年1月9日星期日
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 5000); //2002年3月28日星期四
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 10000); //2015年12月5日星期六 
	(void)DisplayDate(endDate);

	endDate = dateOp.DateAddDays(beginDate, 20000); //2043年4月22日星期三 
	(void)DisplayDate(endDate);

}

int _tmain(int argc, _TCHAR* argv[])
{
	Date thisDate;
	thisDate.date_year = 2014;
	thisDate.date_month = 2;
	thisDate.date_day = 21;

	Date endDate = thisDate;

	DateOp thisDateOp(thisDate);
	(void)DisplayDate(thisDate);

	//不同类型用例测试.
	(void)testLeapYearOrNot();
	(void)testDaysInMonth();
	(void)testDataAddmonths();
	(void)testDataAddDays();
	return 0;
}

         代码通过VS2010编译通过，测试案例都没有bug。有发现bug可以留言，一起改进完善，谢谢！

          2014-12-23  am0:01思于家中床前

作者：铭毅天下

转载请标明出处，原文地址：http://blog.csdn.net/laoyang360/article/details/41604621

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按月、按天计算失效日期的代码实现