Delphi - Read File To StringList, then delete and write back to file

Question

I'm currently working on a program to generate the hashes of files, in Delphi 2010. As part of this I have a option to create User Presets, e.g. pre-defined choice of hashing algo's which the user can create/save/delete. I have the create and load code working fine. It uses a ComboBox and loads from a file "fhpre.ini", inside this file is the users presets stored in format of:-

PresetName
PresetCode (a 12 digit string using 0 for don't hash and 1 for do)

On application loading it loads the data from this file into the ComboBox and an Array with the ItemIndex of ComboBox matching the corrisponding correct string of 0's and 1's in the Array.

Now I need to implement a feature to have the user delete a preset from the list. So far my code is as follows,

procedure TForm1.Panel23Click(Sender : TObject);

var
fil : textfile;
contents : TStringList;
x,i : integer;
filline : ansistring;
filestream : TFileStream;

begin //Start Procedure

//Load data into StringList
contents := TStringList.Create;
fileStream := TFileStream.Create((GetAppData+'\RFA\fhpre.ini'), fmShareDenyNone);
Contents.LoadFromStream(fileStream);
fileStream.Destroy();

//Search for relevant Preset
i := 0;
if ComboBox4.Text <> Contents[i] then
begin
Repeat
i := i + 1;
Until ComboBox4.Text = Contents[i];
end;

contents.Delete(i); //Delete Relevant Preset Name
contents.Delete(i); //Delete Preset Digit String

//Write StringList back to file.
AssignFile(fil,(GetAppData+'\RFA\fhpre.ini'));
ReWrite(fil);
for i := 0 to Contents.Count -1 do
WriteLn(Contents[i]);
CloseFile(fil);
Contents.Free;
end;

However if this is run, I get a 105 error when it gets to the WriteLn section. I'm aware that the code isn't great, for example doesn't have checks for presets with same name, but that will come, I want to get the base code working first then can tweak and add extra checks etc.

Any help would be appreciated.

Answer 1

You are aware, I hope, that TStringList has LoadFromFile and SaveToFile methods?

And if you can't use those methods for some reason, why use a stream for reading but WriteLn for writing?

To write to a file using WriteLn, you must specify the file as the first argument:

 WriteLn(fil, Contents[i]);

without the argument it tries to write to the console (which is presumably not available in your Windows application). Error 105 is "File not open for output".

Answer 2

Since you are dealing with an .ini file, you should be using the TIniFile class to manipulate its contents as needed. That will make your configuration and code much easier to maintain.