Solved

Float Conversion

Posted on 1997-05-09
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Last Modified: 2010-04-06
procedure TForm1.txtPressureChange(Sender: TObject);
var
    Pressure: Single;
begin
    if length(txtPressure.Text) > 0 then
    begin
      Label1.Caption := FormatFloat('0.00', StrToFloat(txtPressure.Text));
      Pressure := StrToFloat(Label1.Caption)
    end;
    Label2.Caption := FloatToStr(Pressure)
end;

This is my attempt to ensure that the variable Pressure is the same as entered in txtPressure,
however the results I get are as follows:

txtPressure.Text      '10.1'

Label1.Caption            '10.10'

Label2.Caption            '10.1000003814697'

so Pressure = 10.1000003814697 not 10.1, how can I fix this please.

Antony
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Comment
Question by:antony burden
  • 3
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6 Comments
 
LVL 2

Accepted Solution

by:
javiertb earned 50 total points
ID: 1336035
Instead of using FloatToStr use FloatToStrF where you can set Precission and Digits. Look up this function in delphi on-line help.
0
 

Author Comment

by:antony burden
ID: 1336036
Label2 was only used to show the strange value, I need to ensure that variable Pressure is exactly the same as the value entered in txtPressure, I'm not worried about Label1 or Label2, just Pressure.Please can someone correctly answer this problem.Antony
0
 
LVL 2

Expert Comment

by:javiertb
ID: 1336037
Try this:

var
    idecimals,idigits: integer;
    Pressure: single;
begin
  idecimals:=pos(',',txtPressure.Text); // decimals separator
  if (idecimals>0) then
     idigits:=length(txtPressure.Text)-idecimals
  else
    idigits:=0;
  Pressure:=strtofloat(txtPressure.text);
  Label1.Caption:=                                  FloattoStrF(txtPressure.Text,ffFixed,7,idigits);
end;

Label1 should be the same as txtPressure.
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Author Comment

by:antony burden
ID: 1336038
Thankyou, I'll try this very soon.Thanks a lot.Antony
0
 

Author Comment

by:antony burden
ID: 1336039
Could you explain why the number displayed is so wierd?
0
 
LVL 2

Expert Comment

by:javiertb
ID: 1336040
No idea. It isn't logical. If you introduce '10,10' why you get 10,1000543 or whatever instead of 10,1000000 (what would be the logical result)?? Better to ask Borland for this.
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