[Dev-C++] illegal operation in while loop

[Alan T. <ala...@3n...>]

All of a sudden, I started getting an "illegal operation" in a while =
loop.  I cut everything out of the loop, but I still get the error.  The =
pertinent code is shown below.  Any ideas?  I have used the same input =
file from the start.

            If I change "input_file.getline(buffer, 200, '\t')" to =
"input_file.get(c)" then the program does not encounter an error.

                                                                         =
                                  Thanks, Alan

 char *buffer =3D "";
 char c;
=20
 ifstream input_file ("test_tab_win.txt");
 =20
 while (input_file.getline(buffer, 200, '\t'))
       {
          // nothing here
       }
=20