Author: Arthur Young

How to patch binary files? 

Answer:

Replaces a string in a file with new string. 

1   procedure TForm1.Button1Click(Sender: TObject);
2   var
3     f: file;
4     l: Longint;
5     FileName, oldstring, newstring, s: string;
6   begin
7     oldstring := 'old string';
8     newstring := 'new string';
9     FileName := 'c:\YourFileName.xyz';
10  
11    s := oldstring;
12    AssignFile(f, FileName);
13    Reset(f, 1);
14    for l := 0 to FileSize(f) - Length(oldstring) - 1 do
15    begin
16      Application.ProcessMessages;
17      Seek(f, l);
18      BlockRead(f, oldstring[1], Length(oldstring));
19      if oldstring = s then
20      begin
21        Seek(f, l);
22        BlockWrite(f, newstring[1], Length(newstring));
23        ShowMessage('String successfully replaced!');
24      end;
25      Application.ProcessMessages;
26    end;
27    CloseFile(f);
28  end;