Can't get GLFW to link

Question

I am trying to compile the below test program:

#include 

int main(int argc, char** argv) {
    if(!glfwInit()) {
        return -1;
    }

             


        

Answer 1

The problem is that the glfw libraries are being specified to the linker before the object file that depends on them. ld searches libraries to resolve dependencies only for the dependencies that it knows about at the point in list of files it's processing. So when ld is searching libglfw.a it doesn't know about the glfwInit dependency in main.o yet. ld (by default) doesn't go back an search the library again.

Try:

$(EXECUTABLE):
    $(CXX) $(CXXFLAGS) $(LIB_DIR) -o $@ $(OBJECTS)  $(LDFLAGS)

Also the libraries should probably be specified in a LDLIBS (or LIBS) variable - LDFLAGS is conventionally use for linker options:

CXX = clang++
CXXFLAGS = -Wall -std=c++0x
LDLIBS = -lglfw -lGL -lGLU

OBJ_DIR = bin
LIB_DIR = -L/usr/lib
INC_DIR = -I/usr/include

SOURCE = main.cpp
OBJECTS = ${SOURCE:%.cpp=$(OBJ_DIR)/%.o}
EXECUTABLE = hello

all: init $(OBJECTS) $(EXECUTABLE)

$(EXECUTABLE):
    $(CXX) $(LDFLAGS) $(LIB_DIR) -o $@ $(OBJECTS) $(LDLIBS)

$(OBJ_DIR)/%.o: %.cpp
    $(CXX) $(INC_DIR) -c $< -o $@

init:
    @mkdir -p "$(OBJ_DIR)"

clean:
    @rm -rf $(OBJ_DIR) $(EXECUTABLE)