I get linker errors when trying to compile my opengl project using gcc

Question

I am using glfw and glew to create the window and it's giving me linker errors. How can I fix it. This is my first time installing glfw and glew so I could've missed a step in the installation. Any help?

I compile my code using just:

gcc main.c

I know there are some linker flags, but glfw and glew are not a part of them.

I use linux with the gcc compiler.

This is my code:

#define GLEW_STATIC
#include <stdio.h>
#include <stdlib.h>
#include <GL/glew.h>
#include <GL/glfw3.h>
#include <stdbool.h>

int main(){
   glewExperimental = true;
   if(!glfwInit()){
    printf("failed to initialize GLFW\n");
    return -1;
   }
   glfwWindowHint(GLFW_SAMPLES, 4);
   glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
   glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
   glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

   GLFWwindow* window;
   window = glfwCreateWindow(1024, 768, "Game", NULL, NULL);
   if(window == NULL){
    printf("Sorry to say this, but your OpenGL version must be 3.3 or above! Thanks for playing, but to continue you must update your video card drivers or if you use an old GPU you may have to replace it with a new one to play this game. I will be developing my game for OpenGL 1 and 2 soon so stay on touch.");
    glfwTerminate();
    return -1;
   }
   glfwMakeContentCurrent(window);
   glewExperimental = true;
   if(glewInit() != GLEW_OK){
    printf("Failed to initilize GLEW");
    return -1;
   }

}

This is the error log:

/usr/bin/ld: /tmp/cc74wuFz.o: in function `main':
main.c:(.text+0xe): undefined reference to `glewExperimental'
/usr/bin/ld: main.c:(.text+0x14): undefined reference to `glfwInit'
/usr/bin/ld: main.c:(.text+0x3d): undefined reference to `glfwWindowHint'
/usr/bin/ld: main.c:(.text+0x4c): undefined reference to `glfwWindowHint'
/usr/bin/ld: main.c:(.text+0x5b): undefined reference to `glfwWindowHint'
/usr/bin/ld: main.c:(.text+0x6a): undefined reference to `glfwWindowHint'
/usr/bin/ld: main.c:(.text+0x79): undefined reference to `glfwWindowHint'
/usr/bin/ld: main.c:(.text+0x9a): undefined reference to `glfwCreateWindow'
/usr/bin/ld: main.c:(.text+0xbb): undefined reference to `glfwTerminate'
/usr/bin/ld: main.c:(.text+0xd3): undefined reference to `glfwMakeContentCurrent'
/usr/bin/ld: main.c:(.text+0xd9): undefined reference to `glewExperimental'
/usr/bin/ld: main.c:(.text+0xdf): undefined reference to `glewInit'
collect2: error: ld returned 1 exit status

Answer 1

I suggest to compile with a command similar to

gcc -Wall -Wextra -g $(pkg-config --cflags opengl glfw3) main.c \
     $(pkg-config --libs opengl glfw3) -o prog

Of course (before trying that) you need to install OpenGL related libraries, probably using (as root) the following command

aptitude install libopengl-dev libglfw3-dev

Be sure to read the documentation of GCC and the documentation of GDB and the documentation of binutils and the documentation of pkg-config.

PS. You could get inspiration from the source code of existing open source projects, such as GNU emacs or RefPerSys.