Patch binary files

Problem/Question/Abstract:

How to patch binary files?

Answer:

Replaces a string in a file with new string.

procedure TForm1.Button1Click(Sender: TObject);
var
f: file;
l: Longint;
FileName, oldstring, newstring, s: string;
begin
oldstring := 'old string';
newstring := 'new string';
FileName := 'c:\YourFileName.xyz';

s := oldstring;
AssignFile(f, FileName);
Reset(f, 1);
for l := 0 to FileSize(f) - Length(oldstring) - 1 do
begin
Application.ProcessMessages;
Seek(f, l);
BlockRead(f, oldstring[1], Length(oldstring));
if oldstring = s then
begin
Seek(f, l);
BlockWrite(f, newstring[1], Length(newstring));
ShowMessage('String successfully replaced!');
end;
Application.ProcessMessages;
end;
CloseFile(f);
end;