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Using the Lazarus IDE => General => Topic started by: alaa123456789 on July 08, 2022, 10:01:13 pm

Title: using stdconvs,convutils units in convertor demo
Post by: alaa123456789 on July 08, 2022, 10:01:13 pm

hi all ,

i am trying to make a demo for units convertor using the above mentioned units in uses section
after long research i reached to some knowledge about it (here incomplete code)

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, StdConvs, ConvUtils, Forms, Controls, Graphics, Dialogs,
9.   StdCtrls;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     ComboBox1: TComboBox;
17.     ListBox1: TListBox;
18.  
19.     procedure ComboBox1Change(Sender: TObject);
20.     procedure FormCreate(Sender: TObject);
21.     procedure changefamily(Sender: TObject);
22.   private
23.     fam: TConvFamily;
24.     fams: TConvFamilyArray;
25.   public
26.  
27.   end;
28.  
29. var
30.   Form1: TForm1;
31.  
32. implementation
33.  
34. {$R *.lfm}
35.  
36. { TForm1 }
37.  
38. procedure TForm1.FormCreate(Sender: TObject);
39. var
40.  
41.   len: integer;
42.  
43. begin
44.   GetConvFamilies(fams);
45.   Len := Length(Fams);
46.   if (Len <> 0) then
47.  
48.     for len := Low(Fams) to High(Fams) do
49.       //ComboBox1.Items.Add(format('%d: %s',[ord(fam),ConvFamilyToDescription(fam)]));
50.       ComboBox1.Items.Add(format('%s', [ConvFamilyToDescription(len)]));
51.   ComboBox1.ItemIndex := 0;
52.   changefamily(self);
53. end;
54.  
55. procedure TForm1.ComboBox1Change(Sender: TObject);
56. begin
57.   changefamily(self);
58. end;
59.  
60.  
61.  
62. procedure TForm1.changefamily(Sender: TObject);
63. var
64.   atypes: TConvTypeArray;
65.   i: integer;
66. begin
67.   //fggf
68.   ListBox1.Clear;
69.   fam := fams[ComboBox1.ItemIndex];
70.   GetConvTypes(fam, atypes);
71.   for i := Low(atypes) to High(atypes) do
72.     ListBox1.Items.Add(format('%s', [ConvTypeToDescription(i)]));
73.  
74. end;
75.  
76. end.
77.  
78.  

but the results in the listbox are not correct (attched png)
what is wrong with it , here i attached also the demo project
please advise how to make it correct
thanks

Title: Re: using stdconvs,convutils units in convertor demo
Post by: wp on July 08, 2022, 10:44:27 pm

Rather than

Quote from: alaa123456789 on July 08, 2022, 10:01:13 pm

Code: Pascal  [Select][+][-]

1. procedure TForm1.changefamily(Sender: TObject);
2. ...
3.   for i := Low(atypes) to High(atypes) do
4.     ListBox1.Items.Add(format('%s', [ConvTypeToDescription(i)]));

use

Code: Pascal  [Select][+][-]

1.   for i in atypes do
2.     ListBox1.Items.Add(ConvTypeToDescription(i));

This is because atypes is a TConvTypeArray which is nothing else than an array of integer. And Low() always returns 0 for a dynamic array. A bit strange kind of programming style was inherited from Delphi here...

BTW, there have been many changes recently in the conversion units, e.g. https://gitlab.com/freepascal.org/fpc/source/-/issues/39801, https://gitlab.com/freepascal.org/fpc/source/-/issues/39778, etc.

Title: Re: using stdconvs,convutils units in convertor demo
Post by: marcov on July 08, 2022, 11:31:21 pm

Quote from: wp on July 08, 2022, 10:44:27 pm

BTW, there have been many changes recently in the conversion units, e.g. https://gitlab.com/freepascal.org/fpc/source/-/issues/39801, https://gitlab.com/freepascal.org/fpc/source/-/issues/39778, etc.

http://www.stack.nl/~marcov/mergelogs32/convutils.html

Title: Re: using stdconvs,convutils units in convertor demo
Post by: alaa123456789 on July 09, 2022, 08:05:54 pm

Quote from: wp on July 08, 2022, 10:44:27 pm

This is because atypes is a TConvTypeArray which is nothing else than an array of integer. And Low() always returns 0 for a dynamic array. A bit strange kind of programming style was inherited from Delphi here...

thanks WP , for all people in this forum
please watch and download the full sample from here

https://youtu.be/ZBV_ijOoG7k (https://youtu.be/ZBV_ijOoG7k)