Question

I am coding in OS X
Here is my Makefile:

#makefile for stack_5_1
# Yitong Zhou

stack_5 : main.o Stack.o LIFO_Stack.o Peekback_Stack.o
    g++ -o stack_5 main.o Stack.o LIFO_Stack.o Peekback_Stack.o
main.o: main.cpp Stack.h LIFO_Stack.h Peekback_Stack.h
    g++ -c main.cpp
Stack.o: Stack.cpp Stack.h
    g++ -c Stack.cpp
LIFO_Stack.o: LIFO_Stack.cpp LIFO_Stack.h
    g++ -c LIFO_Stack.cpp
Peekback_Stack.o: Peekback_Stack.cpp Peekback_Stack.h
    g++ -c Peekback_Stack.cpp

clean: 
    rm -rf *.o stack_5 

The error:

.....  // very very long 
Dwarf Exception Unwind Info (__eh_frame) in Stack.o
Dwarf Exception Unwind Info (__eh_frame) in LIFO_Stack.o
Dwarf Exception Unwind Info (__eh_frame) in Peekback_Stack.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
make: *** [stack_5] Error 1

What is the difference between gcc and g++? Why does my compile fail when I replace g++ with gcc?

By the way, how could I ensure that my makefile could be run correctly in Cygwin, linux, OS X and maybe other environment.

Answer 1

gcc is for compiling C by default

g++ is for compiling C++ by default

The primary difference is that g++ transparently adds the options -x c++ (use C++) and -lstdc++ (use C++ standard library).

Try this Makefile:

stack_5: main.o Stack.o LIFO_Stack.o Peekback_Stack.o

main.o: main.cpp Stack.h LIFO_Stack.h Peekback_Stack.h

Stack.o: Stack.cpp Stack.h

LIFO_Stack.o: LIFO_Stack.cpp LIFO_Stack.h

Peekback_Stack.o: Peekback_Stack.cpp Peekback_Stack.h

make will automatically fill in the sensible rules based on the file extensions.

Also take a look at the -MM gcc option. It will automatically generate the correct make dependencies (which header files) so you don’t need to maintain this list manually. There is more in the make manual and gcc manual about how to use it.