Solved

Delphi 4 : Incrementing the result of 'Now' by a negative amount of minutes

Posted on 2006-11-30
8
671 Views
Last Modified: 2011-09-20
Hello.

I have the below line:

 if (StrToDateTime(QueryNextRun.FieldByName('report_lastrun').AsString) > IncMinute(Now, -180)) then

Which fails to work, as I am using Delphi 4, and I guess IncMinute is in the later versions.

So my question is, how can I achieve the above in Delphi 4?

Just want to compare 2 date/time values, where the 1st comes from a SQL table (Format: dd/mm/yyyy HH:MM:SS) and the second is Now minus about 180 minutes
0
Comment
Question by:wbstech
8 Comments
 
LVL 27

Accepted Solution

by:
kretzschmar earned 500 total points
ID: 18044590
use now - 180/1440

meikl ;-)
0
 
LVL 6

Expert Comment

by:wimmeyvaert
ID: 18044624
When calculating with date/time, you have the following rule :
1 exact day = 1 (So Now + 1 = tomorrow).

So :
1 day = 1
--> 1 minute = ( 1 / 24 ) / 60 = 6,9444444444444444444444444444444e-4
--> 180 minutes = 6,9444444444444444444444444444444e-4 * 180 = 0,125


In a Delphi Example :

var
  aDate: TDateTime;

  aDate := Now;
  showmessage( FormatDateTime( 'dd/mm/yyyy hh:nn:ss:zzz', aDate ) +
               #13#10 +
               FormatDateTime( 'dd/mm/yyyy hh:nn:ss:zzz', aDate-StrToFloat(Edit5.Text) ) );


This shows you exactly the current date/time and current date/time minus 180 minutes.

So, instead of IncMinute(Now, -180) you can use (Now-0.125)

Best regards,

The Mayor.
0
 
LVL 6

Expert Comment

by:wimmeyvaert
ID: 18044639
damn, too slow again ! ;-)
0
 
LVL 6

Expert Comment

by:wimmeyvaert
ID: 18044649
Btw, I found IncMinute in the DateUtil-Unit of the RxLib !

Didn't know about that function.

So, if you have RxLib installed, it is enough to include the DateUtil in your uses-clause.
0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 
LVL 6

Expert Comment

by:wimmeyvaert
ID: 18044687
In this unit DateUtil.pas there is :

function IncMinute(ATime: TDateTime; Delta: Integer): TDateTime;
begin
  Result := IncTime(ATime, 0, Delta, 0, 0);
end;


and of course also :

function IncTime(ATime: TDateTime; Hours, Minutes, Seconds,
  MSecs: Integer): TDateTime;
begin
  Result := ATime + (Hours div 24) + (((Hours mod 24) * 3600000 +
    Minutes * 60000 + Seconds * 1000 + MSecs) / MSecsPerDay);
  if Result < 0 then Result := Result + 1;
end;

the variable MSecsPerDay = 24 * 60 * 60 * 1000
0
 
LVL 6

Expert Comment

by:wimmeyvaert
ID: 18044761
Or you can make you own IncMinute-Function Like this :

function IncMinute( ATime: TDateTime; Delta: Integer ): TDateTime;
begin
  Result := aDate + ( ( ( 1 / 24 ) / 60) * Delta );
end;
0
 
LVL 45

Expert Comment

by:aikimark
ID: 18044851
reference for future readers:
NOW (Windows timestamp) is a floating point numeric value with the integer value being the number of days since 1899-12-31 (yyyy-mm-dd format) and the decimal value being a percentage of the date (starting at midnight).

There fractional part of the day is usually displayed down to a one second granularity, but it is accurate down to 1/100 second.

To avoid unnecessary divisions, remember these conversion constants:
86400 - seconds in a day
1440 - minutes in a day
24 - hours in a day (duh)

==================================
If you need a more granular or more reliable timestamp, you would avoid NOW and use a Multi-Media timing value or a Tick timing value.
0
 
LVL 4

Author Comment

by:wbstech
ID: 18053589
Thanks for the massive amount of detail folks. Didn't expect all that! :-)
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

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

Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
Sending a Secure fax is easy with eFax Corporate (http://www.enterprise.efax.com). First, just open a new email message. In the To field, type your recipient's fax number @efaxsend.com. You can even send a secure international fax — just include t…
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…

911 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

Need Help in Real-Time?

Connect with top rated Experts

16 Experts available now in Live!

Get 1:1 Help Now