Saving a value even after program is closed and reopened - delphi

Question

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.

Answer 1

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:
Create a new VCL application.
Add a field FMyNumber: Integer to the main form.
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;
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:
Create a new VCL application.
Add a field FMyNumber: Integer to the main form.
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;
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!