print "Field 1 & 2 Separate or Combined? ";
  chomp($_=<STDIN>);
  lc($_);
# always sets $OPER to 'c'
  $_ eq 's' ? $OPER='s' : $OPER='c';

# but this works as expected:
  $OPER='s' if ($_ eq 's');
  $OPER='c' if ($_ eq 'c');