How to limit quantity of fractional numbers of a given variable in Delphi

Question

Do anyone knows how do I format the quantity of displayed fractional numbers of a variable in Delphi (in my program, it is being used the variable Real).

i.e:

            3.14159265359

integer value|fractional value

Based on the example, all I want is this number to be displayed as 3.14 (note that this is just an example. In my program, the user is going to input the real value).

I'm looking forward to display this value in a label. Is there any way to do that? If yes, how?

REFERENCE -> link to exemplify exactly what I want to do, but in Delphi (instead of Java, which is the language used in the link below):

How I can to limit decimal numbers of double variable?

Look at [`SysUtils.FormatFloat()`](http://docwiki.embarcadero.com/Libraries/en/System.SysUtils.FormatFloat) and related functions. — Remy Lebeau, Jul 08 '20 at 01:04
Use the function ``FloatToStrF`` with “format type“ ``ffFixed``, digits = 2 and precision at least = 3 — Delphi Coder, Jul 08 '20 at 01:28
@FARS if you answeer your own question with the answer provided by Delphi Coder, you may actually gain some reputation points. which is good! — H.Hasenack, Jul 09 '20 at 20:17

score 0 · Answer 1 · answered Jul 25 '20 at 09:54

You can do this very easily using Delphi's built-in function:

FloatToStrF();

This function, takes a real value and returns a string with a precision point, in your example 3.14

The code would look as follows:

FloatToStr(ffFixed, 12 ,2);

First specify the type of formatting, in this case it will be a fixed value.
Second, is the integer value size before the decimal point.
Third argument is the number of decimal values after the decimal point.

Hope this helped!

score 0 · Accepted Answer · answered May 05 '21 at 19:56

Code sample which successfully implements what I was looking forward to do:

Var
    a, b, c: Real;
begin
      a := StrToFloat(txt1.Text);
      b := INT(a);
      c := frac(ABS(a)) + 0.000000000000001;

Full code sample:

unit Unit10;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TfrmM4E1 = class(TForm)
    btn1: TButton;
    lbl1: TLabel;
    txt1: TEdit;
    lbl2: TLabel;
    procedure btn1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frmM4E1: TfrmM4E1;

implementation

{$R *.dfm}

procedure TfrmM4E1.btn1Click(Sender: TObject);
Var
    a, b, c: Real;
begin
      a := StrToFloat(txt1.Text);
      b := INT(a);
      c := frac(ABS(a)) + 0.000000000000001;
      lbl1.Caption := FloatToStr(b);
      lbl2.Caption := FloatToStr(c);
end;

end.

Quick explanation: this is the code implementation of a UI, which has a button, a text field (which get the fractional value), and two labels, one of them displays the integer portion of the entered number, and the other label, displays the fractional portion of the entered number.

Variable "a" stores the inserted value;

Variable "b" stores the integer value from variable "a";

Variable "c" stores the fractional value from variable "a", plus a number correction since "c" lacks 0.000000000000001 in the displayed final value.

Finally, labels "lbl1", and "lbl2" shows the values of variables "b" and "c", respectivaly.

How to limit quantity of fractional numbers of a given variable in Delphi

2 Answers2