TNumberBox and scientific notation (exponential format)

[Gord P 14]

I typically use TEdits or StringGrids to let the user input numbers.  Sometimes for a given input, the number can either a regular float (123.456) or required to be entered with scientific notation (1.23456e11).  I thought maybe TNumberBox might be helpful with number input (i.e. automatically handle only entering valid numerics) so I checked it out but I am unable to get it to allow the user to enter an exponent.

 

Based on something online I think the the Microsoft's NumberBox control, which I assume TNumberBox is emulating or wrapping, has the ability do this.  Could be wrong here too though.

 

Is it not able to do this or is it just me?  I have fooled around with the DisplayFormat property but no joy.

 

 

[programmerdelphi2k 237]

maybe....

Quote

  NumberBox1.Mode          := TNumberBoxMode.nbmFloat;
  NumberBox1.Decimal       := 0; // ??
  NumberBox1.DisplayFormat := '0.0E+;0.0E-;Hello';

 

[Gord P 14]

Thanks for the suggestion.  Unfortunately it doesn't give me the desired behavior.

 

I would like the user to be able to enter a number such as 1.234E9.  The NumberBox will not allow typing in an 'E'.

[David Heffernan 2354]

What's wrong with a simple edit control? 

[Uwe Raabe 2064]

3 hours ago, Gord P said:

The NumberBox will not allow typing in an 'E'.

Seems like a feature request in QP would be appropriate.

[Gord P 14]

7 hours ago, David Heffernan said:

What's wrong with a simple edit control? 

Not too much really and that is what I have been using - along with some code to check or prevent incorrect input.  I was just checking to see if the TNumberBox control would have that built in and maybe some additional features since the word "Number" is in the name of the control.

[programmerdelphi2k 237]

maybe some like this ???

• NOTE: when replace a value on NumberBox (old values) was verifyed that "e" will be accepted!!! then needs more tests... ok?
• NOTE2: NumberBox1.Text is always "old value", better works to "NumberBox1.VALUExxxxx"

type
  TForm1 = class(TForm)
    NumberBox1: TNumberBox;
    procedure FormCreate(Sender: TObject);
  private
    procedure MyOnValidChar(AChar: char; var AValidated: boolean);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  FormatSettings.DecimalSeparator := '.';
  //
  NumberBox1.Mode           := TNumberBoxMode.nbmFloat;
  NumberBox1.Decimal        := 20; // ??
  NumberBox1.DisplayFormat  := '0.0E+;0.0E-;Hello';
  //
  NumberBox1.OnValidateChar := MyOnValidChar;  // <------
end;

procedure TForm1.MyOnValidChar(AChar: char; var AValidated: boolean);
begin
  if CharInSet(AChar, ['E', 'e']) then
    begin
      if NumberBox1.ValueFloat = 0 then // eNNNN.NNN ???
        AValidated := false
      else
        AValidated := string(NumberBox1.Text).ToLower.CountChar('e') = 0; // NOT "Neeee"
    end;
end;

 

 

Edited March 16, 2023 by programmerdelphi2k

[Gord P 14]

Thanks for that.  In the end though if I have to add code, it's not much better than the Edit control for now.  It's not a big deal, I was just wondering if I was missing something on this control, but I guess not.