Solved

Need advanced date and day calculations in C++

Posted on 2006-06-19
7
1,620 Views
Last Modified: 2008-05-03
We are developing a proprietary task scheduler (just like windows scheduler) for a product.
I desperately need a ready-made source code or algorithms or anything that will help me.

I need something like: First/Second/Third/Fourth/Last  Monday/Tuesday/Wed/Thur...Sunday of a particular Month.

Task will be customised to run at any one of above combinations chosen by user.

Any help will be greatly appreciated.

Thanks in Advance.

0
Comment
Question by:chinawal
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 12

Assisted Solution

by:rajeev_devin
rajeev_devin earned 25 total points
ID: 16939385
0
 
LVL 5

Author Comment

by:chinawal
ID: 16943475
Thanks for the reply Rajeev.

Actually we have already developed the code for the schedular.What we are interested in dates calculation part of the schedular.we need to get the dates calculation in Terms of Monthly,weekly and Daily , those are aviable with the windows
schedular.

Thanks ,
Uma
0
 
LVL 39

Assisted Solution

by:itsmeandnobodyelse
itsmeandnobodyelse earned 25 total points
ID: 16950090
The following should do the job.

#include <windows.h>
#include <time.h>

enum Weekday { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY };
enum DayInMonth { FIRSTDAY, SECONDDAY, THIRDDAY, FOURTHDAY, LASTDAY  };

int daysMonth[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

int getDayOfMonth(int year, int month, Weekday wd, DayInMonth dim)
{
     struct tm tm = { 0 };
     tm.tm_mday = 1;
     tm.tm_mon  = month-1;
     tm.tm_year = year - 1900;
     time_t  tt = mktime(&tm);
     struct tm* ptm = localtime(&tt); // get day of week to struct tm
     
     // calculate first weekday
     int day = 1 + (wd - ptm->tm_wday);
     if (dim != LASTDAY)
         return day + 7 * dim;

     day += 28;
     if (day <= daysMonth[month-1])
         return day;
     if (month == 2 && day == 29 && year%4 == 0)
         return 29;
     return day - 7;
}

Regards, Alex
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 4

Accepted Solution

by:
e_tadeu earned 50 total points
ID: 16969080
0
 
LVL 4

Expert Comment

by:markscha
ID: 21494619
I was looking for code that does this very thing, and I came across this thread.
The code submitted by "itsmeandnobodyelse" does not work.  Perhaps there is a typo somewhere, but I don't see how it can possibly work.
As an example, I cut and pasted the code into a simple program, and I get peculiar results:
e.g. second Sunday in 3/2008 is the 2nd, an obviously invalid result:
from code:  Second Sun  in 3/2008 is: 2

If we go through the algorithm for the second Sunday in 3/2008:
desired day, wd, is Sunday=0.
First day of 3/2008 is a Saturday=6 should be in ptm->tm_wday.
day = 1 + (wd - ptm->tm_wday) = 1 + (0 - 6), so day = -5
dim (i.e. SECONDAY = 1) is not equal to LASTDAY (4), so we are returning day+7*dim = -5+7*1 = 2

The rest of the code is garbage, too, including the incorrectly handled leap year calculation (no leap  year in years ending with 00).

DOES ANYONE CHECK THIS STUFF?
#include <iostream>
#include <time.h>
#include <string>
 
enum Weekday { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY };
enum DayInMonth { FIRSTDAY, SECONDDAY, THIRDDAY, FOURTHDAY, LASTDAY  };
 
int daysMonth[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
 
int getDayOfMonth(int year, int month, Weekday wd, DayInMonth dim)
{
     struct tm tm = { 0 };
     tm.tm_mday = 1;
     tm.tm_mon  = month-1;
     tm.tm_year = year - 1900;
     time_t  tt = mktime(&tm);
     struct tm* ptm = localtime(&tt); // get day of week to struct tm
     
     // calculate first weekday 
     int day = 1 + (wd - ptm->tm_wday);
     if (dim != LASTDAY)
         return day + 7 * dim;
 
     day += 28; 
     if (day <= daysMonth[month-1])
         return day;
     if (month == 2 && day == 29 && year%4 == 0)
         return 29;
     return day - 7;
}
 
 
int main()
{
	std::string weekDayName[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
	std::string whichDay[] = { "First", "Second", "Third", "Fourth", "Last" };
	
	int year = 2008;
	int month = 3;
	Weekday wday = SUNDAY;
	DayInMonth which = SECONDDAY;
 
	int dayOfMonth = getDayOfMonth(year, month, wday, which);
	
	std::cout << whichDay[which] << " " << weekDayName[wday] << "  " << "in " << month << "/" << year ;
	std::cout << " is: " << dayOfMonth << std::endl;
	return 0;

Open in new window

0
 
LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 21512882
>>>> int day = 1 + (wd - ptm->tm_wday);
   
The prog should work correct if changing the above line into

 int day = 1 + ((7+ wd - ptm->tm_wday)%7);


>>>> The rest of the code is garbage, too, including the incorrectly handled leap

2000 was a leap year because it can be divided by 400 without rest. So the above algorithm covers all years between 1901 and 2099 what seems to be a sufficient range for normal date calculations.

You could make it work for all dates by

     if (month == 2 && day == 29 && 
         (year%4 == 0 && (year%100 != 0 || year%400 == 0)))
         return 29;

I currently am on vacancies and can't compile and test the above.

Regards, Alex
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Unlike C#, C++ doesn't have native support for sealing classes (so they cannot be sub-classed). At the cost of a virtual base class pointer it is possible to implement a pseudo sealing mechanism The trick is to virtually inherit from a base class…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.

628 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question