The header file <iostream.h> should be included before "expr.h"
is compiled. If you include <iostream.h> before "expr.h" in
"expr.cpp" and "asgn3.cpp", there should be no problem.
I think a better solution is to include <iostream.h> directly
in "expr.h". I will be changing the online version of "expr.h"
to have this include statement.
- Dave Simpson
CMPT 212 instructor