/* compile with gcc idx_shad_lang.c -lglfw -lGL -o idx_shad_lang */

#include <GLFW/glfw3.h>
#include <stdlib.h>
#include <stdio.h>

typedef const GLubyte *(APIENTRYP PFNGLGETSTRINGIPROC) (GLenum name, GLuint index);
PFNGLGETSTRINGIPROC getStringi = NULL;

int main(void)
{
    GLFWwindow* window = NULL;
    GLint numLanguages = 0, i;
    if (!glfwInit())
        exit(EXIT_FAILURE);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    window = glfwCreateWindow(640, 480, "Example", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }
    glfwMakeContextCurrent(window);

    printf("Shading language version: %s\n", glGetString(GL_SHADING_LANGUAGE_VERSION));

    glGetIntegerv(GL_NUM_SHADING_LANGUAGE_VERSIONS, &numLanguages);
    printf("%d total languages\n", numLanguages);

    getStringi = (PFNGLGETSTRINGIPROC)glfwGetProcAddress("glGetStringi");
    for(i = 0; i < numLanguages && getStringi; i++)
      printf("language %d: %s\n", i, getStringi(GL_SHADING_LANGUAGE_VERSION, i));
}