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Read/Save contents

Posted on 2001-09-14
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Last Modified: 2010-04-06
How can I use TStream to save and read the contents of 4 listboxs and 2 memos to "Demo.dat" file? Something like database. Exmaples please.
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Question by:TCSCode
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2 Comments
 
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Expert Comment

by:bugroger
ID: 6483809
Hi,

Have a look at these two functions:

{
 SaveIT(ListBox1, ListBox2, ListBox3, ListBox4, Memo1, Memo2, 'C:\Demo.dat');
LoadIt(ListBox1, ListBox2, ListBox3, ListBox4, Memo1, Memo2, 'C:\Demo.dat');
}

Procedure SaveIT(LB1, LB2, LB3, LB4 : TListBox; M1, M2 : TMemo; FileName : String);
VAR
 FS           : TFileStream;
 DummyStream  : TMemoryStream;
 Size         : Integer;

Begin
 FS          := TFileStream.Create(FileName, fmCreate or fmSHAREDENYNONE);
 DummyStream := TMemoryStream.Create;

 LB1.Items.SaveToStream(DummyStream);
 Size := DummyStream.Size;
 FS.Write(Size, 4);
 FS.Write(DummyStream.Memory^, Size);

 LB2.Items.SaveToStream(DummyStream);
 Size := DummyStream.Size;
 FS.Write(Size, 4);
 FS.Write(DummyStream.Memory^, Size);

 LB3.Items.SaveToStream(DummyStream);
 Size := DummyStream.Size;
 FS.Write(Size, 4);
 FS.Write(DummyStream.Memory^, Size);

 LB4.Items.SaveToStream(DummyStream);
 Size := DummyStream.Size;
 FS.Write(Size, 4);
 FS.Write(DummyStream.Memory^, Size);

 M1.Lines.SaveToStream(DummyStream);
 Size := DummyStream.Size;
 FS.Write(Size, 4);
 FS.Write(DummyStream.Memory^, Size);

 M2.Lines.SaveToStream(DummyStream);
 Size := DummyStream.Size;
 FS.Write(Size, 4);
 FS.Write(DummyStream.Memory^, Size);

 DummyStream.Free;
 FS.Free;
End;

Procedure LoadIT(LB1, LB2, LB3, LB4 : TListBox; M1, M2 : TMemo; FileName : String);
VAR
 FS           : TFileStream;
 DummyStream  : TMemoryStream;
 Size         : Integer;

Begin
 FS          := TFileStream.Create(FileName, fmOpenRead or fmSHAREDENYNONE);
 DummyStream := TMemoryStream.Create;

 FS.Read(Size, 4);
 DummyStream.Size := Size;
 FS.Read(DummyStream.Memory^, Size);
 LB1.Items.LoadFromStream(DummyStream);

 FS.Read(Size, 4);
 DummyStream.Size := Size;
 FS.Read(DummyStream.Memory^, Size);
 LB2.Items.LoadFromStream(DummyStream);

 FS.Read(Size, 4);
 DummyStream.Size := Size;
 FS.Read(DummyStream.Memory^, Size);
 LB3.Items.LoadFromStream(DummyStream);

 FS.Read(Size, 4);
 DummyStream.Size := Size;
 FS.Read(DummyStream.Memory^, Size);
 LB4.Items.LoadFromStream(DummyStream);

 FS.Read(Size, 4);
 DummyStream.Size := Size;
 FS.Read(DummyStream.Memory^, Size);
 M1.Lines.LoadFromStream(DummyStream);

 FS.Read(Size, 4);
 DummyStream.Size := Size;
 FS.Read(DummyStream.Memory^, Size);
 M2.Lines.LoadFromStream(DummyStream);

 DummyStream.Free;
 FS.Free;
End;
0
 

Accepted Solution

by:
duti earned 300 total points
ID: 6484085
const
  sFileName ='demo.dat';
{---------------------------------------------------------------------------
  TForm1.Button1Click
---------------------------------------------------------------------------}
procedure TForm1.Button1Click(Sender: TObject);
Begin
  // you can save as much listboxes/memos as you want,
  // without additional coding in the save/load routines.
  SaveData( [ ListBox1, Memo1, ListBox2, listbox3, Memo2 ] );
end;

{---------------------------------------------------------------------------
  TForm1.Button2Click
---------------------------------------------------------------------------}
procedure TForm1.Button2Click(Sender: TObject);
begin
  LoadData; // everything works automagically
end;

{---------------------------------------------------------------------------
  TForm1.SaveData
---------------------------------------------------------------------------}
procedure TForm1.SaveData(aComp : array of TComponent);
var
  stream : TFileStream;
  i      : integer;

  procedure _Save(const sName, sData : string);
  var iLength : integer;
  begin
    iLength := length(sName);
    stream.Write(iLength, sizeof(iLength));
    stream.Write(pchar(sName)^, length(sName));

    iLength := length(sData);
    stream.Write(iLength, sizeof(iLength));
    stream.Write(pchar(sData)^, length(sData));
  end;
begin
  stream := TFileStream.Create(sFileName, fmCreate or fmShareDenyNone);
  try
    for i := low(aComp) to high(aComp) do
      if aComp[i] is TListbox then _Save(aComp[i].Name, TListbox(aComp[i]).Items.Text)
      else if aComp[i] is TMemo then _Save(aComp[i].Name, TMemo(aComp[i]).Lines.Text);
  finally
    stream.Free;
  end;
end;

{---------------------------------------------------------------------------
  TForm1.LoadData
---------------------------------------------------------------------------}
procedure TForm1.LoadData;
var
  stream       : TFileStream;
  iLength      : integer;
  iBytesRead   : integer;
  sName        : string;
  sText        : string;
  Comp         : TComponent;
begin
  stream := TFileStream.Create(sFileName, fmOpenRead or fmShareDenyNone);
  try
    repeat
      iBytesRead := stream.Read(iLength, SizeOf(iLength));
      if iBytesRead > 0 then
        begin
          SetLength(sName, iLength);
          stream.Read(pchar(sName)^, iLength);

          stream.Read(iLength, SizeOf(iLength));
          SetLength(sText, iLength);
          stream.Read(pchar(sText)^, iLength);
          Comp := FindComponent(sName);
          if Comp <> nil then
            begin
              if Comp is TListBox then TListBox(Comp).Items.Text := sText
              else if Comp is TMemo then TMemo(Comp).Lines.Text := sText;
            end;
        end;
    until iBytesRead = 0;
  finally
    stream.Free;
  end;
end;
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