CODEWITHSUNDEEP
delphidelphi-xe2delphi-2010
Fuzail
Fuzail

Reputation: 81

Saving a value even after program is closed and reopened

I would like to know how to save the contents of a "variable" after program is closed and reopened.

for eg: iCount:=0; inc(iCount)=1;

when i close the program and reopen i want iCount to contain 1. Thank you.

Upvotes: 0

Views: 377

Answers (1)

Andreas Rejbrand
Andreas Rejbrand

Reputation: 108948

There are many ways to do this. You need to save the value somewhere: in a file, in the Windows registry, in the cloud, ...

File

Perhaps the easiest approach is to use an INI file. Try this:

  1. Create a new VCL application.

  2. Add a field FMyNumber: Integer to the main form.

  3. To the main form, add the following methods (and make sure to include IniFiles and IOUtils in the implementation section's uses list):

    function TForm1.GetSettingsFileName: TFileName;
begin
  Result := TPath.GetHomePath + '\Fuzail\TestApp';
  ForceDirectories(Result);
  Result := Result + '\settings.ini';
end;

procedure TForm1.LoadSettings;
var
  Ini: TMemIniFile;
begin
  Ini := TMemIniFile.Create(GetSettingsFileName);
  try
    FMyNumber := Ini.ReadInteger('Settings', 'MyNumber', 0);
  finally
    Ini.Free;
  end;
end;

procedure TForm1.SaveSettings;
var
  Ini: TMemIniFile;
begin
  Ini := TMemIniFile.Create(GetSettingsFileName);
  try
    Ini.WriteInteger('Settings', 'MyNumber', FMyNumber);
    Ini.UpdateFile;
  finally
    Ini.Free;
  end;
end;

  4. Now make sure to call these when your application is starting and shutting down:

    procedure TForm1.FormCreate(Sender: TObject);
begin
  LoadSettings;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  SaveSettings;
end;

    Now the value of FMyNumber is saved between the sessions!

Registry

Another common approach, probably, is to use the registry. Try this:

  1. Create a new VCL application.

  2. Add a field FMyNumber: Integer to the main form.

  3. To the main form, add the following methods (and make sure to include Registry in the implementation section's uses list):

    procedure TForm1.LoadSettings;
var
  Reg: TRegistry;
begin
  Reg := TRegistry.Create;
  try
    Reg.RootKey := HKEY_CURRENT_USER;
    if Reg.OpenKey('\Software\Fuzail\TestApp', False) then
      try
        if Reg.ValueExists('MyNumber') then
          FMyNumber := Reg.ReadInteger('MyNumber')
      finally
        Reg.CloseKey;
      end;
  finally
    Reg.Free;
  end;
end;

procedure TForm1.SaveSettings;
var
  Reg: TRegistry;
begin
  Reg := TRegistry.Create;
  try
    Reg.RootKey := HKEY_CURRENT_USER;
    if Reg.OpenKey('\Software\Fuzail\TestApp', True) then
      try
        Reg.WriteInteger('MyNumber', FMyNumber);
      finally
        Reg.CloseKey;
      end;
  finally
    Reg.Free;
  end;
end;

  4. Now make sure to call these when your application is starting and shutting down:

    procedure TForm1.FormCreate(Sender: TObject);
begin
  LoadSettings;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  SaveSettings;
end;

    Again the value of FMyNumber is saved between the sessions!

Upvotes: 6

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