GLAD failing to initialize

Question

I'm having a problem where the following lines of code always print "Failed to initialize glad" and then exits the program:

if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
    std::cout << "Failed to initialize GLAD" << std::endl;
    return -1;
}

I have been using https://learnopengl.com/ as a guide and have been following the steps in the getting started section. I am writing this using Visual Studio, I have moved the glad.c source file into the build to get this working and added the header files to the same location where I specified the GLFW header would be, but I haven't been able to find anyone with a problem similar to mine.

Commenting out return -1; line results in an access violation exception, so it is definitely here that the program is having trouble.

Here is the entire program in case there is something else I am missing:

#include "stdafx.h"
#include <GLFW/glfw3.h>
#include <glad/glad.h>
#include <iostream>

using namespace std;

void init_glfw();

void framebuffer_size_callback(GLFWwindow*, int, int);

int main(int argc, char **argv)
{
    init_glfw();

    GLFWwindow* window = glfwCreateWindow(800, 600, "Lab3", NULL, NULL);

    if (window == NULL)
    {
        cout << "Failed to create GLFW window" << endl;
        glfwTerminate();
        return -1;
    }


    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    glViewport(0, 0, 800, 600);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);


    while (!glfwWindowShouldClose(window))
    {
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}

void init_glfw()
{
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
}

void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    glViewport(0, 0, width, height);
}

Answer 1

You never made the window's OpenGL context current via glfwMakeContextCurrent(). Unlike other OpenGL windowing frameworks GLFW doesn't leave the window's OpenGL context current when glfwCreateWindow() succeeds.

Call glfwMakeContextCurrent() after glfwCreateWindow() succeeds:

GLFWwindow* window = glfwCreateWindow(800, 600, "Lab3", NULL, NULL);
if (window == NULL)
{
    cout << "Failed to create GLFW window" << endl;
    glfwTerminate();
    return -1;
}

glfwMakeContextCurrent( window );

if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
    std::cout << "Failed to initialize GLAD" << std::endl;
    return -1;
}