Undefined reference to SDL_*many* - c++

Question

This is my makefile:
CFLAGS = -Wall -pedantic -pedantic-errors -g -lSDL -lSDL_image
CC = g++
OBJ = Point.o Personaje.o Juego.o EventHandler.o
all: main
#%.o: %.cpp %.h
# $(CC) -c $(CFLAGS) $<
bin: other $(OBJ)
Point.o: Point.cpp Point.h
$(CC) -c $(CFLAGS) $<
Personaje.o: Personaje.cpp Personaje.h
$(CC) -c $(CFLAGS) $<
Juego.o: Juego.cpp Juego.h
$(CC) -c $(CFLAGS) $<
EventHandler.o: EventHandler.cpp EventHandler.h
$(CC) -c $(CFLAGS) $<
main: $(OBJ)
cd ../vista/; make
cp ../vista/*.o .
rm ../vista/*.o
g++ $(CFLAGS) $(OBJ) Pantalla.o Imagen.o main.cpp -o main
clean:
rm *.o;
rm main
PHONY: main
When I compile with "make" I get the following errors:
EventHandler.cpp:17: undefined reference to `SDL_PollEvent'
Pantalla.o: In function `Pantalla::initialize(int, int, int, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)':
Pantalla.cpp:6: undefined reference to `SDL_Init'
Pantalla.cpp:9: undefined reference to `SDL_SetVideoMode'
Pantalla.cpp:14: undefined reference to `SDL_WM_SetCaption'
and many other errors.
The header of "Pantalla.h" contains this line:
#include "SDL/SDL.h"
And I already installed the SDL packages.
I don't know what I'm doing wrong... please help!

Answer 1

CFLAGS = -Wall -pedantic -pedantic-errors -g -lSDL -lSDL_image
This isn't good. You're mixing compiler flags (warnings and debug) with linker information (which libraries you need to link to). Use two separate variables for that:
CFLAGS = -Wall -pedantic -pedantic-errors -g
LIBS = -lSDL -lSDL_image
Then when you compile (but don't link, i.e. when you generate the .o files), only use $(CFLAGS) (like you have now). But when you do link (to produce the final executable), add the linker directives.
g++ $(CFLAGS) -o main main.cpp $(OBJ) Pantalla.o Imagen.o $(LIBS)
The order you put your objects and libraries is important.

Answer 2

One problem is that you are using exactly the same flags for compilation and linking. The compiler doesn't use libraries; the linker doesn't know about pedantic.
A bigger problem is that your -lSDL -lSDL_image appears too early in the link command, g++ $(CFLAGS) $(OBJ) Pantalla.o Imagen.o main.cpp -o main. The linker won't look into libSDL.a or libSDL_image.a (or their equivalents) because there are no unresolved external references at the point where you specified the search. Put the -lSDL -lSDL_image options just before the -o option.