Question

I have a string that contains null characters.

I’ve tried to save it to a file with this code:

myStringList.Text := myString;
myStringList.SaveToFile('c:\myfile');

Unfortunately myStringList.Text is empty if the source string has a null character at the beginning.

I thought only C string were terminated by a null character, and Delphi was always fine with it.

How to save the content of the string to a file?

Answer 1

I think you mean “save a string that has #0 characters in it”.

If that’s the case, don’t try and put it in a TStringList. In fact, don’t try to save it as a string at all; just like in C, a NULL character (#0 in Delphi) causes the string to be truncated at times. Use a TFileStream and write it directly as byte content:

var
  FS: TFileStream;
begin
  FS := TFileStream.Create('C:\MyFile', fmCreate);
  try
    FS.Write(myString[1], Length(myString) * SizeOf(Char));
  finally
    FS.Free;
  end;
end;

To read it back:

var
  FS: TFileStream;
begin
  FS := TFileStream.Create('C:\MyFile', fmOpenRead);
  try
    SetLength(MyString, FS.Size);
    FS.Read(MyString[1], FS.Size);
  finally
    FS.Free;
  end;
end;