An ATL replacement for COleDateTime

Use this in place of COleDateTime when using ATL. No MFC required.

Header file:

// DateTime.h: interface for the CDateTime class.
//
//////////////////////////////////////////////////////////////////////

#ifndef AFX_DATETIME_H__A3E968D9_455B_11D2_9288_00E02921E6D0__INCLUDED_
#define AFX_DATETIME_H__A3E968D9_455B_11D2_9288_00E02921E6D0__INCLUDED_

#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000

#include 
#include 

#include 

class CDateTime;
class CDateTimeSpan;
////////////////////////////////////////////////////////////////////////////

// CDateTime class helpers

#define AFX_OLE_DATETIME_ERROR (-1)

////////////////////////////////////////////////////////////////////////////

// CDateTime class

class CDateTime
{
    // Constructors
public:
    static CDateTime PASCAL GetCurrentTime();
    
    CDateTime();
    
    CDateTime(const CDateTime& dateSrc);
    CDateTime(const VARIANT& varSrc);
    CDateTime(DATE dtSrc);
    
    CDateTime(time_t& timeSrc);
    CDateTime(const SYSTEMTIME& systimeSrc);
    CDateTime(const FILETIME& filetimeSrc);
    
    CDateTime(int nYear, int nMonth, int nDay,
              int nHour, int nMin, int nSec);
    CDateTime(WORD wDosDate, WORD wDosTime);
    
    // Attributes
public:
    enum DateTimeStatus
    {
          valid = 0,
          invalid = 1,    // Invalid date (out of range, etc.)
          null = 2,       // Literally has no value
    };
    
    DATE m_dt;
    DateTimeStatus m_status;
    
    void SetStatus(DateTimeStatus status) { m_status=status;}
    DateTimeStatus GetStatus() const { return m_status;}
    
    int GetYear() const;
    int GetMonth() const;       // month of year (1 = Jan)
    int GetDay() const;         // day of month (0-31)
    int GetHour() const;        // hour in day (0-23)
    int GetMinute() const;      // minute in hour (0-59)
    int GetSecond() const;      // second in minute (0-59)
    int GetDayOfWeek() const;   // 1=Sun, 2=Mon, ..., 7=Sat
    int GetDayOfYear() const;   // days since start of year, Jan 1 = 1
    
    // Operations
public:
    const CDateTime& operator=(const CDateTime& dateSrc);
    const CDateTime& operator=(const VARIANT& varSrc);
    const CDateTime& operator=(DATE dtSrc);
    
    const CDateTime& operator=(const time_t& timeSrc);
    const CDateTime& operator=(const SYSTEMTIME& systimeSrc);
    const CDateTime& operator=(const FILETIME& filetimeSrc);
    
    BOOL operator==(const CDateTime& date) const;
    BOOL operator!=(const CDateTime& date) const;
    BOOL operator<(const CDateTime& date) const;
    BOOL operator>(const CDateTime& date) const;
    BOOL operator<=(const CDateTime& date) const;
    BOOL operator>=(const CDateTime& date) const;
    
    // DateTime math
    CDateTime operator+(const CDateTimeSpan& dateSpan) const;
    CDateTime operator-(const CDateTimeSpan& dateSpan) const;
    const CDateTime& operator+=(const CDateTimeSpan dateSpan);
    const CDateTime& operator-=(const CDateTimeSpan dateSpan);
    
    // DateTimeSpan math
    CDateTimeSpan operator-(const CDateTime& date) const;
    
    operator DATE() const;
    int SetDateTime(int nYear, int nMonth, int nDay,
          int nHour, int nMin, int nSec);
    int SetDate(int nYear, int nMonth, int nDay);
    int SetTime(int nHour, int nMin, int nSec);
    BOOL ParseDateTime(LPCTSTR lpszDate, DWORD dwFlags = 0,
          LCID lcid = LANG_USER_DEFAULT);
    
    
    // formatting
    _bstr_t Format(DWORD dwFlags = 0, LCID lcid = LANG_USER_DEFAULT) const;
    
    _bstr_t Format(LPCTSTR lpszFormat) const;
    //CComString Format(UINT nFormatID) const;
    
    // Implementation
protected:
    void CheckRange();
    friend CDateTimeSpan;
};



////////////////////////////////////////////////////////////////////////////

// CDateTimeSpan class
class CDateTimeSpan
{
    // Constructors
public:
    CDateTimeSpan();
    
    CDateTimeSpan(double dblSpanSrc);
    CDateTimeSpan(const CDateTimeSpan& dateSpanSrc);
    CDateTimeSpan(long lDays, int nHours, int nMins, int nSecs);
    
    // Attributes
public:
    enum DateTimeSpanStatus
    {
          valid = 0,
          invalid = 1,    // Invalid span (out of range, etc.)
          null = 2,       // Literally has no value
    };
    
    double m_span;
    DateTimeSpanStatus m_status;
    
    void SetStatus(DateTimeSpanStatus status) { m_status=status;}
    DateTimeSpanStatus GetStatus() const { return m_status;}
    
    
    double GetTotalDays() const;    // span in days (about -3.65e6 to 3.65e6)
    double GetTotalHours() const;   // span in hours (about -8.77e7 to 8.77e6)
    double GetTotalMinutes() const; // span in minutes (about -5.26e9 to 5.26e9)
    double GetTotalSeconds() const; // span in seconds (about -3.16e11 to 3.16e11)
    long GetDays() const;           // component days in span
    long GetHours() const;          // component hours in span (-23 to 23)
    long GetMinutes() const;        // component minutes in span (-59 to 59)
    long GetSeconds() const;        // component seconds in span (-59 to 59)
    
    // Operations
public:
    const CDateTimeSpan& operator=(double dblSpanSrc);
    const CDateTimeSpan& operator=(const CDateTimeSpan& dateSpanSrc);
    
    BOOL operator==(const CDateTimeSpan& dateSpan) const;
    BOOL operator!=(const CDateTimeSpan& dateSpan) const;
    BOOL operator<(const CDateTimeSpan& dateSpan) const;
    BOOL operator>(const CDateTimeSpan& dateSpan) const;
    BOOL operator<=(const CDateTimeSpan& dateSpan) const;
    BOOL operator>=(const CDateTimeSpan& dateSpan) const;
    
    // DateTimeSpan math
    CDateTimeSpan operator+(const CDateTimeSpan& dateSpan) const;
    CDateTimeSpan operator-(const CDateTimeSpan& dateSpan) const;
    const CDateTimeSpan& operator+=(const CDateTimeSpan dateSpan);
    const CDateTimeSpan& operator-=(const CDateTimeSpan dateSpan);
    CDateTimeSpan operator-() const;
    
    operator double() const;
    
    void SetDateTimeSpan(long lDays, int nHours, int nMins, int nSecs);
    
    // formatting
    _bstr_t Format(LPCTSTR pFormat) const;
    //CComString Format(UINT nID) const;
    
    // Implementation
public:
    void CheckRange();
    friend CDateTime;
};

#endif // AFX_DATETIME_H__A3E968D9_455B_11D2_9288_00E02921E6D0__INCLUDED_

Source file:

// DateTime.cpp: implementation of the CDateTime class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "DateTime.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#endif

////////////////////////////////////////////////////////////////////////////

// CDateTime class HELPER definitions

// Verifies will fail if the needed buffer size is too large
#define MAX_TIME_BUFFER_SIZE    128         // matches that in
timecore.cpp
#define MIN_DATE                (-657434L)  // about year 100
#define MAX_DATE                2958465L    // about year 9999


// Half a second, expressed in days
#define HALF_SECOND  (1.0/172800.0)

// One-based array of days in year at month start
static int rgMonthDays[13] =
{0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365};

static BOOL OleDateFromTm(WORD wYear, WORD wMonth, WORD wDay,
                                  WORD wHour, WORD wMinute, WORD wSecond, DATE& dtDest);
static BOOL TmFromOleDate(DATE dtSrc, struct tm& tmDest);
static void TmConvertToStandardFormat(struct tm& tmSrc);
static double DoubleFromDate(DATE dt);
static DATE DateFromDouble(double dbl);

////////////////////////////////////////////////////////////////////////////

// CDateTime class
CDateTime::CDateTime()
{
    m_dt=0;
    SetStatus(invalid);
}

CDateTime::CDateTime(const CDateTime& dateSrc)
{
    m_status=dateSrc.m_status;
    m_dt=dateSrc.m_dt;
}

CDateTime::CDateTime(const VARIANT& varSrc)
{
    if (varSrc.vt != VT_DATE)
    {
        
          _variant_t varTemp(varSrc);
          varTemp.ChangeType(VT_DATE);
          m_dt = varTemp.date;
    }
    else
    {
          m_dt = varSrc.date;
          SetStatus(valid);
    }
    
}

CDateTime::CDateTime(DATE dtSrc)
{
    m_dt = dtSrc;
    SetStatus(valid);
}

CDateTime::CDateTime(time_t& timeSrc)
{
    // Convert time_t to struct tm
    tm *ptm = localtime(&timeSrc);
    
    if (ptm != NULL)
    {
          m_status = OleDateFromTm((WORD)(ptm->tm_year + 1900),
               (WORD)(ptm->tm_mon + 1), (WORD)ptm->tm_mday,
               (WORD)ptm->tm_hour, (WORD)ptm->tm_min,
               (WORD)ptm->tm_sec, m_dt) ? valid : invalid;
    }
    else
    {
          // Local time must have failed (timsSrc before 1/1/70 12am)
          m_dt=0;
          SetStatus(invalid);
    }
    
    
}

CDateTime::CDateTime(const SYSTEMTIME& systimeSrc)
{
    m_status = OleDateFromTm(systimeSrc.wYear, systimeSrc.wMonth,
          systimeSrc.wDay, systimeSrc.wHour, systimeSrc.wMinute,
          systimeSrc.wSecond, m_dt) ? valid : invalid;
    
    
}

CDateTime::CDateTime(const FILETIME& filetimeSrc)
{
    // Assume UTC FILETIME, so convert to LOCALTIME
    FILETIME filetimeLocal;
    if (!FileTimeToLocalFileTime( &filetimeSrc, &filetimeLocal))
    {
          m_status = invalid;
    }
    else
    {
          // Take advantage of SYSTEMTIME -> FILETIME conversion
          SYSTEMTIME systime;
          m_status = FileTimeToSystemTime(&filetimeLocal, &systime) ?
valid : invalid;
        
          // At this point systime should always be valid, but...
          if (GetStatus() == valid)
          {
               m_status = OleDateFromTm(systime.wYear, systime.wMonth,
                    systime.wDay, systime.wHour, systime.wMinute,
                    systime.wSecond, m_dt) ? valid : invalid;
          }
    }
    
    
}

/////

CDateTime PASCAL CDateTime::GetCurrentTime()
{
    return CDateTime(::time(NULL));
}

int CDateTime::GetYear() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_year;
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetMonth() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_mon;
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetDay() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_mday;
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetHour() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_hour;
    
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetMinute() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_min;
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetSecond() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_sec;
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetDayOfWeek() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_wday;
    else
          return AFX_OLE_DATETIME_ERROR;
}

int CDateTime::GetDayOfYear() const
{
    struct tm tmTemp;
    
    if (GetStatus() == valid && TmFromOleDate(m_dt, tmTemp))
          return tmTemp.tm_yday;
    else
          return AFX_OLE_DATETIME_ERROR;
}

const CDateTime& CDateTime::operator=(const VARIANT& varSrc)
{
    if (varSrc.vt != VT_DATE)
    {
        
          _variant_t varTemp(varSrc);
          varTemp.ChangeType(VT_DATE);
          m_dt = varTemp.date;
    }
    else
    {
          m_dt = varSrc.date;
          SetStatus(valid);
    }
    
    return *this;
}

const CDateTime& CDateTime::operator=(DATE dtSrc)
{
    m_dt = dtSrc;
    SetStatus(valid);
    
    return *this;
}

const CDateTime& CDateTime::operator=(const time_t& timeSrc)
{
    // Convert time_t to struct tm
    tm *ptm = localtime(&timeSrc);
    
    if (ptm != NULL)
    {
          m_status = OleDateFromTm((WORD)(ptm->tm_year + 1900),
               (WORD)(ptm->tm_mon + 1), (WORD)ptm->tm_mday,
               (WORD)ptm->tm_hour, (WORD)ptm->tm_min,
               (WORD)ptm->tm_sec, m_dt) ? valid : invalid;
    }
    else
    {
          // Local time must have failed (timsSrc before 1/1/70 12am)
    }
    
    return *this;
}

const CDateTime& CDateTime::operator=(const SYSTEMTIME& systimeSrc)
{
    m_status = OleDateFromTm(systimeSrc.wYear, systimeSrc.wMonth,
          systimeSrc.wDay, systimeSrc.wHour, systimeSrc.wMinute,
          systimeSrc.wSecond, m_dt) ? valid : invalid;
    
    return *this;
}

const CDateTime& CDateTime::operator=(const FILETIME& filetimeSrc)
{
    // Assume UTC FILETIME, so convert to LOCALTIME
    FILETIME filetimeLocal;
    if (!FileTimeToLocalFileTime( &filetimeSrc, &filetimeLocal))
    {
          m_status = invalid;
    }
    else
    {
          // Take advantage of SYSTEMTIME -> FILETIME conversion
          SYSTEMTIME systime;
          m_status = FileTimeToSystemTime(&filetimeLocal, &systime) ?
valid : invalid;
        
          // At this point systime should always be valid, but...
          if (GetStatus() == valid)
          {
               m_status = OleDateFromTm(systime.wYear, systime.wMonth,
                    systime.wDay, systime.wHour, systime.wMinute,
                    systime.wSecond, m_dt) ? valid : invalid;
          }
    }
    
    return *this;
}

BOOL CDateTime::operator<(const CDateTime& date) const
{
    //ASSERT(GetStatus() == valid);
    //ASSERT(date.GetStatus() == valid);
    
    // Handle negative dates
    return DoubleFromDate(m_dt) < DoubleFromDate(date.m_dt);
}

BOOL CDateTime::operator>(const CDateTime& date) const
{   //ASSERT(GetStatus() == valid);
    //ASSERT(date.GetStatus() == valid);
    
    // Handle negative dates
    return DoubleFromDate(m_dt) > DoubleFromDate(date.m_dt);
}

BOOL CDateTime::operator<=(const CDateTime& date) const
{
    //ASSERT(GetStatus() == valid);
    //ASSERT(date.GetStatus() == valid);
    
    // Handle negative dates
    return DoubleFromDate(m_dt) <= DoubleFromDate(date.m_dt);
}


BOOL CDateTime::operator>=(const CDateTime& date) const
{
    //ASSERT(GetStatus() == valid);
    //ASSERT(date.GetStatus() == valid);
    
    // Handle negative dates
    return DoubleFromDate(m_dt) >= DoubleFromDate(date.m_dt);
}

CDateTime CDateTime::operator+(const CDateTimeSpan& dateSpan) const
{
    CDateTime dateResult;    // Initializes m_status to valid
    
    // If either operand NULL, result NULL
    if (GetStatus() == null || dateSpan.GetStatus() == null)
    {
          dateResult.SetStatus(null);
          return dateResult;
    }
    
    // If either operand invalid, result invalid
    if (GetStatus() == invalid || dateSpan.GetStatus() == invalid)
    {
          dateResult.SetStatus(invalid);
          return dateResult;
    }
    
    // Compute the actual date difference by adding underlying dates
    dateResult = DateFromDouble(DoubleFromDate(m_dt) + dateSpan.m_span);
    
    // Validate within range
    dateResult.CheckRange();
    
    return dateResult;
}

CDateTime CDateTime::operator-(const CDateTimeSpan& dateSpan) const
{
    CDateTime dateResult;    // Initializes m_status to valid
    
    // If either operand NULL, result NULL
    if (GetStatus() == null || dateSpan.GetStatus() == null)
    {
          dateResult.SetStatus(null);
          return dateResult;
    }
    
    // If either operand invalid, result invalid
    if (GetStatus() == invalid || dateSpan.GetStatus() == invalid)
    {
          dateResult.SetStatus(invalid);
          return dateResult;
    }
    
    // Compute the actual date difference by subtracting underlying dates
    dateResult = DateFromDouble(DoubleFromDate(m_dt) - dateSpan.m_span);
    
    // Validate within range
    dateResult.CheckRange();
    
    return dateResult;
}

CDateTimeSpan CDateTime::operator-(const CDateTime& date) const
{
    CDateTimeSpan spanResult;
    
    // If either operand NULL, result NULL
    if (GetStatus() == null || date.GetStatus() == null)
    {
          spanResult.SetStatus(CDateTimeSpan::null);
          return spanResult;
    }
    
    // If either operand invalid, result invalid
    if (GetStatus() == invalid || date.GetStatus() == invalid)
    {
          spanResult.SetStatus(CDateTimeSpan::invalid);
          return spanResult;
    }
    
    // Return result (span can't be invalid, so don't check range)
    return DoubleFromDate(m_dt) - DoubleFromDate(date.m_dt);
}

int CDateTime::SetDateTime(int nYear, int nMonth, int nDay,
                                    int nHour, int nMin, int nSec)
{
    return m_status = OleDateFromTm((WORD)nYear, (WORD)nMonth,
          (WORD)nDay, (WORD)nHour, (WORD)nMin, (WORD)nSec, m_dt) ?
valid : invalid;
}

BOOL CDateTime::ParseDateTime(LPCTSTR lpszDate, DWORD dwFlags, LCID
                              lcid)
{
    USES_CONVERSION;
    //CString strDate = lpszDate;
    
    SCODE sc;
    if (FAILED(sc = VarDateFromStr((LPOLESTR)T2COLE(lpszDate), lcid,
          dwFlags, &m_dt)))
    {
          if (sc == DISP_E_TYPEMISMATCH)
          {
               // Can't convert string to date, set 0 and invalidate
               m_dt = 0;
               SetStatus(invalid);
               return FALSE;
          }
          else if (sc == DISP_E_OVERFLOW)
          {
               // Can't convert string to date, set -1 and invalidate
               m_dt = -1;
               SetStatus(invalid);
               return FALSE;
          }
          else
          {
               // TRACE0("\nCDateTime VarDateFromStr call failed.\n\t");
               // if (sc == E_OUTOFMEMORY)
               //  AfxThrowMemoryException();
               // else
               //  AfxThrowOleException(sc);
               m_dt=0;
               SetStatus(invalid);
               return FALSE;
          }
        
    }
    
    SetStatus(valid);
    return TRUE;
}


_bstr_t CDateTime::Format(DWORD dwFlags, LCID lcid) const
{
    USES_CONVERSION;
    _bstr_t strDate;
    
    // If null, return empty string
    if (GetStatus() == null)
          return strDate;
    
    // If invalid, return DateTime resource string
    if (GetStatus() == invalid)
    {
          // VERIFY(strDate.LoadString(AFX_IDS_INVALID_DATETIME));
          return strDate;
    }
    
    _variant_t var;
    // Don't need to trap error. Should not fail due to type mismatch
    VarBstrFromDate(m_dt, lcid, dwFlags, &V_BSTR(&var));
    var.vt = VT_BSTR;
    return V_BSTR(&var);
}

_bstr_t CDateTime::Format(LPCTSTR pFormat) const
{
    _bstr_t strDate;
    struct tm tmTemp;
    
    // If null, return empty string
    if (GetStatus() == null)
          return strDate;
    
    // If invalid, return DateTime resource string
    if (GetStatus() == invalid || !TmFromOleDate(m_dt, tmTemp))
    {
          // VERIFY(strDate.LoadString(AFX_IDS_INVALID_DATETIME));
          return strDate;
    }
    
    // Convert tm from afx internal format to standard format
    TmConvertToStandardFormat(tmTemp);
    
    // Fill in the buffer, disregard return value as it's not necessary
    LPTSTR lpszTemp = new TCHAR[MAX_TIME_BUFFER_SIZE];
    _tcsftime(lpszTemp, MAX_TIME_BUFFER_SIZE , pFormat, &tmTemp);
    strDate=lpszTemp;
    delete [] lpszTemp;
    
    return strDate;
}
/*
CComString CDateTime::Format(UINT nFormatID) const
{
CComString strFormat;
strFormat.LoadString(nFormatID);
return Format(strFormat);
}
*/

void CDateTime::CheckRange()
{
    if (m_dt > MAX_DATE || m_dt < MIN_DATE) // about year 100 to about 9999
        
          SetStatus(invalid);
}


////////////////////////////////////////////////////////////////////////////

// CDateTimeSpan class helpers

#define MAX_DAYS_IN_SPAN    3615897L

////////////////////////////////////////////////////////////////////////////

// CDateTimeSpan class

CDateTimeSpan::CDateTimeSpan()
{
    m_span=0;
    SetStatus(invalid);
}

CDateTimeSpan::CDateTimeSpan(double dblSpanSrc)
{
    m_span = dblSpanSrc;
    SetStatus(valid);
}

CDateTimeSpan::CDateTimeSpan(const CDateTimeSpan& dateSpanSrc)
{
    m_span = dateSpanSrc.m_span;
    m_status = dateSpanSrc.m_status;
}

long CDateTimeSpan::GetHours() const
{
    // ASSERT(GetStatus() == valid);
    
    double dblTemp;
    
    // Truncate days and scale up
    dblTemp = modf(m_span, &dblTemp);
    return (long)(dblTemp * 24);
}

long CDateTimeSpan::GetMinutes() const
{
    // ASSERT(GetStatus() == valid);
    
    double dblTemp;
    
    // Truncate hours and scale up
    dblTemp = modf(m_span * 24, &dblTemp);
    return (long)(dblTemp * 60);
}

long CDateTimeSpan::GetSeconds() const
{
    // ASSERT(GetStatus() == valid);
    
    double dblTemp;
    
    // Truncate minutes and scale up
    dblTemp = modf(m_span * 24 * 60, &dblTemp);
    return (long)(dblTemp * 60);
}

const CDateTimeSpan& CDateTimeSpan::operator=(double dblSpanSrc)
{
    m_span = dblSpanSrc;
    SetStatus(valid);
    return *this;
}

const CDateTimeSpan& CDateTimeSpan::operator=(const CDateTimeSpan&
                                                           dateSpanSrc)
{
    m_span = dateSpanSrc.m_span;
    m_status = dateSpanSrc.m_status;
    return *this;
}

CDateTimeSpan CDateTimeSpan::operator+(const CDateTimeSpan& dateSpan)
const
{
    CDateTimeSpan dateSpanTemp;
    
    // If either operand Null, result Null
    if (GetStatus() == null || dateSpan.GetStatus() == null)
    {
        
          dateSpanTemp.SetStatus(null);
          return dateSpanTemp;
    }
    
    // If either operand Invalid, result Invalid
    if (GetStatus() == invalid || dateSpan.GetStatus() == invalid)
    {
          dateSpanTemp.SetStatus(invalid);
          return dateSpanTemp;
    }
    
    // Add spans and validate within legal range
    dateSpanTemp.m_span = m_span + dateSpan.m_span;
    dateSpanTemp.CheckRange();
    
    return dateSpanTemp;
}

CDateTimeSpan CDateTimeSpan::operator-(const CDateTimeSpan& dateSpan)
const
{
    CDateTimeSpan dateSpanTemp;
    
    // If either operand Null, result Null
    if (GetStatus() == null || dateSpan.GetStatus() == null)
    {
          dateSpanTemp.SetStatus(null);
          return dateSpanTemp;
    }
    
    // If either operand Invalid, result Invalid
    if (GetStatus() == invalid || dateSpan.GetStatus() == invalid)
    {
          dateSpanTemp.SetStatus(invalid);
          return dateSpanTemp;
    }
    
    // Subtract spans and validate within legal range
    dateSpanTemp.m_span = m_span - dateSpan.m_span;
    dateSpanTemp.CheckRange();
    
    return dateSpanTemp;
}

void CDateTimeSpan::SetDateTimeSpan(
                                             long lDays, int nHours, int nMins, int nSecs)
{
    // Set date span by breaking into fractional days (all input ranges
    valid)
        m_span = lDays + ((double)nHours)/24 + ((double)nMins)/(24*60) +
          ((double)nSecs)/(24*60*60);
    
    SetStatus(valid);
}

_bstr_t CDateTimeSpan::Format(LPCTSTR pFormat) const
{
    _bstr_t strSpan;
    struct tm tmTemp;
    
    // If null, return empty string
    if (GetStatus() == null)
          return strSpan;
    
    // If invalid, return DateTimeSpan resource string
    if (GetStatus() == invalid || !TmFromOleDate(m_span, tmTemp))
    {
          //VERIFY(strSpan.LoadString(AFX_IDS_INVALID_DATETIMESPAN));
          return strSpan;
    }
    
    // Convert tm from afx internal format to standard format
    TmConvertToStandardFormat(tmTemp);
    
    // Fill in the buffer, disregard return value as it's not necessary
    LPTSTR lpszTemp = new TCHAR[MAX_TIME_BUFFER_SIZE];
    _tcsftime(lpszTemp, MAX_TIME_BUFFER_SIZE, pFormat, &tmTemp);
    strSpan=lpszTemp;
    delete [] lpszTemp;
    
    return strSpan;
}

/*
CComString CDateTimeSpan::Format(UINT nFormatID) const
{
CComString strFormat;
strFormat.LoadString(nFormatID);
return Format(strFormat);
}
*/

void CDateTimeSpan::CheckRange()
{
    if(m_span < -MAX_DAYS_IN_SPAN || m_span > MAX_DAYS_IN_SPAN)
          SetStatus(invalid);
}

////////////////////////////////////////////////////////////////////////////

// CDateTime class HELPERS - implementation

BOOL OleDateFromTm(WORD wYear, WORD wMonth, WORD wDay,
                          WORD wHour, WORD wMinute, WORD wSecond, DATE& dtDest)
{
    // Validate year and month (ignore day of week and milliseconds)
    if (wYear > 9999 || wMonth < 1 || wMonth > 12)
          return FALSE;
    
    //  Check for leap year and set the number of days in the month
    BOOL bLeapYear = ((wYear & 3) == 0) &&
          ((wYear % 100) != 0 || (wYear % 400) == 0);
    
    int nDaysInMonth =
          rgMonthDays[wMonth] - rgMonthDays[wMonth-1] +
          ((bLeapYear && wDay == 29 && wMonth == 2) ? 1 : 0);
    
    // Finish validating the date
    if (wDay < 1 || wDay > nDaysInMonth ||
          wHour > 23 || wMinute > 59 ||
          wSecond > 59)
    {
          return FALSE;
    }
    
    // Cache the date in days and time in fractional days
    long nDate;
    double dblTime;
    
    //It is a valid date; make Jan 1, 1AD be 1
    nDate = wYear*365L + wYear/4 - wYear/100 + wYear/400 +
        
          rgMonthDays[wMonth-1] + wDay;
    
    //  If leap year and it's before March, subtract 1:
    if (wMonth <= 2 && bLeapYear)
          --nDate;
    
    //  Offset so that 12/30/1899 is 0
    nDate -= 693959L;
    
    dblTime = (((long)wHour * 3600L) +  // hrs in seconds
          ((long)wMinute * 60L) +  // mins in seconds
          ((long)wSecond)) / 86400.;
    
    dtDest = (double) nDate + ((nDate >= 0) ? dblTime : -dblTime);
    
    return TRUE;
}

BOOL TmFromOleDate(DATE dtSrc, struct tm& tmDest)
{
    // The legal range does not actually span year 0 to 9999.
    if (dtSrc > MAX_DATE || dtSrc < MIN_DATE) // about year 100 to about
        9999
          return FALSE;
    
    long nDays;             // Number of days since Dec. 30, 1899
    long nDaysAbsolute;     // Number of days since 1/1/0
    long nSecsInDay;        // Time in seconds since midnight
    long nMinutesInDay;     // Minutes in day
    
    long n400Years;         // Number of 400 year increments since 1/1/0
    long n400Century;       // Century within 400 year block (0,1,2 or 3)
    long n4Years;           // Number of 4 year increments since 1/1/0
    long n4Day;             // Day within 4 year block
    //  (0 is 1/1/yr1, 1460 is 12/31/yr4)
    long n4Yr;              // Year within 4 year block (0,1,2 or 3)
    BOOL bLeap4 = TRUE;     // TRUE if 4 year block includes leap year
    
    double dblDate = dtSrc; // tempory serial date
    
    // If a valid date, then this conversion should not overflow
    nDays = (long)dblDate;
    
    // Round to the second
    dblDate += ((dtSrc > 0.0) ? HALF_SECOND : -HALF_SECOND);
    
    nDaysAbsolute = (long)dblDate + 693959L; // Add days from 1/1/0 to
    12/30/1899
        
        dblDate = fabs(dblDate);
    nSecsInDay = (long)((dblDate - floor(dblDate)) * 86400.);
    
    // Calculate the day of week (sun=1, mon=2...)
    //   -1 because 1/1/0 is Sat.  +1 because we want 1-based
    tmDest.tm_wday = (int)((nDaysAbsolute - 1) % 7L) + 1;
    
    // Leap years every 4 yrs except centuries not multiples of 400.
    n400Years = (long)(nDaysAbsolute / 146097L);
    
    // Set nDaysAbsolute to day within 400-year block
    nDaysAbsolute %= 146097L;
    
    // -1 because first century has extra day
    n400Century = (long)((nDaysAbsolute - 1) / 36524L);
    
    // Non-leap century
    if (n400Century != 0)
    {
          // Set nDaysAbsolute to day within century
          nDaysAbsolute = (nDaysAbsolute - 1) % 36524L;
        
          // +1 because 1st 4 year increment has 1460 days
          n4Years = (long)((nDaysAbsolute + 1) / 1461L);
        
          if (n4Years != 0)
               n4Day = (long)((nDaysAbsolute + 1) % 1461L);
          else
          {
               bLeap4 = FALSE;
               n4Day = (long)nDaysAbsolute;
          }
    }
    else
    {
          // Leap century - not special case!
          n4Years = (long)(nDaysAbsolute / 1461L);
          n4Day = (long)(nDaysAbsolute % 1461L);
    }
    
    if (bLeap4)
    {
          // -1 because first year has 366 days
          n4Yr = (n4Day - 1) / 365;
        
          if (n4Yr != 0)
               n4Day = (n4Day - 1) % 365;
    }
    else
    {
          n4Yr = n4Day / 365;
          n4Day %= 365;
    }
    
    // n4Day is now 0-based day of year. Save 1-based day of year, year
    number
        tmDest.tm_yday = (int)n4Day + 1;
    tmDest.tm_year = n400Years * 400 + n400Century * 100 + n4Years * 4 +
        n4Yr;
    
    // Handle leap year: before, on, and after Feb. 29.
    if (n4Yr == 0 && bLeap4)
    {
          // Leap Year
          if (n4Day == 59)
          {
               /* Feb. 29 */
               tmDest.tm_mon = 2;
               tmDest.tm_mday = 29;
            
               goto DoTime;
          }
        
          // Pretend it's not a leap year for month/day comp.
          if (n4Day >= 60)
               --n4Day;
    }
    
    // Make n4DaY a 1-based day of non-leap year and compute
    //  month/day for everything but Feb. 29.
    ++n4Day;
    
    // Month number always >= n/32, so save some loop time */
    for (tmDest.tm_mon = (n4Day >> 5) + 1;
    n4Day > rgMonthDays[tmDest.tm_mon]; tmDest.tm_mon++);
    
    tmDest.tm_mday = (int)(n4Day - rgMonthDays[tmDest.tm_mon-1]);
    
DoTime:
    if (nSecsInDay == 0)
          tmDest.tm_hour = tmDest.tm_min = tmDest.tm_sec = 0;
    else
    {
          tmDest.tm_sec = (int)nSecsInDay % 60L;
          nMinutesInDay = nSecsInDay / 60L;
          tmDest.tm_min = (int)nMinutesInDay % 60;
          tmDest.tm_hour = (int)nMinutesInDay / 60;
    }
    
    return TRUE;
}

void TmConvertToStandardFormat(struct tm& tmSrc)
{
    // Convert afx internal tm to format expected by runtimes (_tcsftime,
    etc)
        tmSrc.tm_year -= 1900;  // year is based on 1900
    tmSrc.tm_mon -= 1;      // month of year is 0-based
    tmSrc.tm_wday -= 1;     // day of week is 0-based
    tmSrc.tm_yday -= 1;     // day of year is 0-based
}

double DoubleFromDate(DATE dt)
{
    // No problem if positive
    if (dt >= 0)
          return dt;
    
    // If negative, must convert since negative dates not continuous
    // (examples: -1.25 to -.75, -1.50 to -.50, -1.75 to -.25)
    double temp = ceil(dt);
    return temp - (dt - temp);
}

DATE DateFromDouble(double dbl)
{
    // No problem if positive
    if (dbl >= 0)
          return dbl;
    
    // If negative, must convert since negative dates not continuous
    // (examples: -.75 to -1.25, -.50 to -1.50, -.25 to -1.75)
    double temp = floor(dbl); // dbl is now whole part
    return temp + (temp - dbl);
}

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