Solved

Problem with int() and trunc() !

Posted on 1998-05-20
7
511 Views
Last Modified: 2010-04-06
Math problem !!!!!!!!

normally int(226.0) returns 226 and
trunc(226.0) returns 226

But I am getting both returning 225
in the code below !


   function EvenCmClasses(OriginalHt:Double) : Double;
   {Converts X to an even cm class, and rounds to two       decimals}
   var
      Ht100, Ht1000, InitialClass : Double;
      CorrectIt : LongInt;
   begin
      Ht100:= OriginalHt*100.0;
      Ht1000:= OriginalHt*1000.0;
      CorrectIt:= Trunc(Ht100);
      InitialClass:= CorrectIt/100.0;
     {InitialClass:= Int(Ht100)/100.0;}

The OriginalHt comes from a sum of a
TOvcPictureArrayEditor set to datatype = ptfDouble

Watches shows OriginalHt = 226

Can anyone give me some help with this ?

John.
0
Comment
Question by:jturpin
7 Comments
 
LVL 2

Expert Comment

by:kjteng
ID: 1346724
i run your code and find the OriginalHt=226 and initialClass=226.
How did you get 225?
what is ptfDouble? a pointer type?
0
 
LVL 5

Expert Comment

by:JimBob091197
ID: 1346725
I agree with kjteng.

Are you trying to round to 2 decimal places?  If so, then your logic is currently "(Int(Num * 100)) / 100".  However, this will always round down, e.g. 226.236 becomes 226.23.  To fix this, add 0.5 after the Int part, i.e. "(Int((Num * 100) + 0.5)) / 100".

Then 226.234 -> 226.23, but 226.235 -> 226.24

In your particular example, I get 226 like kjteng.

Regards,
JB
0
 
LVL 1

Author Comment

by:jturpin
ID: 1346726
I have no idea why it is returning 225. I
was hoping someone could give me some
pointers.

ptfDouble is one of the enumerated values
used by Orpheus. It defines the field data
type as double.

Did you both use orpheus ?

In this routine I need to cut the number off
after the second decimal, without rounding.

John.
0
Ransomware-A Revenue Bonanza for Service Providers

Ransomware – malware that gets on your customers’ computers, encrypts their data, and extorts a hefty ransom for the decryption keys – is a surging new threat.  The purpose of this eBook is to educate the reader about ransomware attacks.

 
LVL 5

Expert Comment

by:JimBob091197
ID: 1346727
Hi again,

I don't use Orpheus, although that shouldn't matter.

This is a very strange problem you have.  If you like, you can e-mail me a sample app which gives the incorrect value, and I can have a look at it.  My e-mail address is davekw@iafrica.com.

Regards,
JB
0
 
LVL 2

Expert Comment

by:kjteng
ID: 1346728
The problem MAT BE due to the actual parameter passed to the function. Check the variable type and also watch the value of the number before it is passed to the function. I suspect that the value passed to the function was 225.99999999 and the .999999 was trucated.

I do not use orpheus though i heard of that before.
0
 
LVL 2

Expert Comment

by:kjteng
ID: 1346729
The problem MAY BE due to the actual parameter passed to the function. Check the variable type and also watch the value of the number before it is passed to the function. I suspect that the value passed to the function was 225.99999999 and the .999999 was trucated.

I do not use orpheus though i heard of that before.
0
 
LVL 3

Accepted Solution

by:
rickpet earned 200 total points
ID: 1346730
As stated earlier by kjteng...you are most likely passing 225.999999999, Delphi's IDE show's this as 226 and not 225.999999999, even though it stores it and handles it as 225.999999999. Step through the code and watch the variables...you'll see what I mean.

Rick

function MyTrunc(value: Double): double;
begin
  value := value * 100.0;
  value := trunc(value);
  result := value/100.0;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  myDouble: double;
begin
  myDouble := 225.999999999;
  Label1.Caption := FloatToStr(MyTrunc(myDouble));
end;

0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Delphi selector screen 2 80
Delphi Form ownership 4 90
how to update exe applicatio from internet ? 6 78
Graphics32 under Delphi 10.1 Berlin 2 67
In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
Introduction I have seen many questions in this Delphi topic area where queries in threads are needed or suggested. I know bumped into a similar need. This article will address some of the concepts when dealing with a multithreaded delphi database…
Microsoft Active Directory, the widely used IT infrastructure, is known for its high risk of credential theft. The best way to test your Active Directory’s vulnerabilities to pass-the-ticket, pass-the-hash, privilege escalation, and malware attacks …
Established in 1997, Technology Architects has become one of the most reputable technology solutions companies in the country. TA have been providing businesses with cost effective state-of-the-art solutions and unparalleled service that is designed…

809 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