//**************************************************************************
// function to attach a file to an input stream
//
// parameter usage :
//          iStr -- exports the stream that the file was attached to
//      filename -- imports the name of the file to be opened and
//                  exports the name of the file that was opened
//**************************************************************************
void openIn(ifstream& iStr, string& filename) {
   iStr.open(filename.c_str());
   while (!iStr) {                                  // unable to open file
      iStr.clear();                                 //  and clear error flag
      cout << "Unable to open file!!! " << filename //  and complain
	   << ".  Re-enter filename --  ";
      getline(cin, filename);                      //  get replacement filename
      iStr.open(filename.c_str());                 //  and try to open it
   }
}