Date Comparision in C programming

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Hi
I need to do the date comparision in plain C.
one is the char Date_1[8] and other is #defined constant "DATE2"
I want to use most recent date from above 2 dates and store it into a file.

Can anybody help me out.

Thanks in advance. :-O

Posted 5-Apr-10 20:12pm

Poonamol

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Solution 2

Thanks for reply.

But my date format is dd/mm/yyyy
How can i compare them?
compare year, month ,date.
I want to use the most recent date. :-O

Posted 5-Apr-10 21:04pm

Poonamol

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Eugen Podsypalnikov · Accepted Answer · 2010-04-05T20:41:00

If it is allowed
to code the date as "YYYYMMDD",

you could use :) :

#define d2 "19001229"
...
{
...
  char d1[8] = {'2','0','1','0','0','4','0','6'};
  int iResult = memcmp(d1 /*address of date1*/,
                       d2 /*address of date2*/,
                       sizeof(d1) /*=8, length to compare*/);
}

Eugen Podsypalnikov · Accepted Answer · 2010-04-05T21:44:00

Another solution to hold and compare the dates :) :

typedef struct sMydate {
  WORD m_wYear;
  BYTE m_byMonth;
  BYTE m_byDay;
 

  sMydate(WORD wYear, BYTE byMonth, BYTE byDay) {
    m_wYear   = wYear;
    m_byMonth = byMonth;
    m_byDay   = byDay;
  }
 

  int Compare(const sMydate& sAnotherDate) {
    LONG lThisDate = MAKELONG(MAKEWORD(m_byDay, m_byMonth), m_wYear);
    LONG lAnotherDate = MAKELONG(MAKEWORD(sAnotherDate.m_byDay,
                                          sAnotherDate.m_byMonth),
                                 sAnotherDate.m_wYear);
 

    return memcmp(&lThisDate, &lAnotherDate, sizeof(LONG));
  }
} MYDATE, *LPMYDATE;
...
const MYDATE sConstDate(1900, 12, 29);
...
{
...
  MYDATE sLocalDate(2010, 04, 06);
  int iResult = sLocalDate.Compare(sConstDate);
...
}

;

CPallini · Accepted Answer · 2010-04-05T22:29:00

Poonamol wrote:
But my date format is dd/mm/yyyy
How can i compare them?
compare year, month ,date.
I want to use the most recent date

The following function returns 1 whenever sDate1 is more recent than sDate2.
Please note: error check is left to the reader.

C++

#include <stdlib.h>

int datecmp(char sdate1[], char sdate2[])
{
  unsigned int y[2], m[2], d[2];
  char * pEnd;
  const char * s[2] = {sdate1, sdate2};
  for (int i=0; i<2; i++)
  {
    d[i] = strtoul(s[i], &pEnd, 10);
    m[i] = strtoul(pEnd+1, &pEnd, 10);
    y[i] = strtoul(pEnd+1, NULL, 10);
  }
  if (y[0] < y[1] )
    return -1;
  else if ( y[0] > y[1])
    return 1;
  if (m[0] < m[1] )
    return -1;
  else if ( m[0] > m[1])
    return 1;
  if (d[0] < d[1] )
    return -1;
  else if ( d[0] > d[1])
    return 1;
  return 0;
}

:)

Date Comparision in C programming

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