What verions of eveything are you using?

Windows 8.1, SDL2 Development library 2.0.7 and the latest version of MinGW, downloaded only yesterday 28/12/2017

Try Windows 10

Windows 10 is not an option for me, is there any other solution you could suggest?

Try the setup process again, sometimes it doesn’t work straight away

My code in codeblocks:

#include <iostream>
#include <GL/glew.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>

const GLint WIDTH = 800, HEIGHT = 600;

int main(int argc, char* args[])
{
  SDL_Init(SDL_INIT_EVERYTHING);
  SDL_GL_SetAttribute( SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE );   SDL_GL_SetAttribute( SDL_GL_CONTEXT_MAJOR_VERSION, 3 );
  SDL_GL_SetAttribute(   SDL_GL_CONTEXT_MINOR_VERSION, 3 );
  SDL_GL_SetAttribute( SDL_GL_STENCIL_SIZE, 8);
 
  SDL_Window *window = SDL_CreateWindow("SDL OpenGL window", 0,0, WIDTH, HEIGHT,                SDL_WINDOW_OPENGL);
 
  SDL_GLContext context = SDL_GL_CreateContext( window );
  glewExperimental = GL_TRUE;
  if(   GLEW_OK != glewInit() )
  { std::cout << "Problem GLEW" << std::endl; return EXIT_FAILURE; }

  glViewport( 0, 0, WIDTH, HEIGHT);
  SDL_Event windowEvent;

  while(true)
  {
     if(SDL_PollEvent( &windowEvent))
     {
        if( SDL_QUIT == windowEvent.type) { break; }
     }
     glClearColor( 0.2f, 0.3f, 0.3f, 1.0f);
     glClear( GL_COLOR_BUFFER_BIT); // draw OpenGL SDL_GL_SwapWindow( window );
  }

  SDL_GL_DeleteContext( context );
  SDL_DestroyWindow( window );
  SDL_Quit(); return EXIT_SUCCESS;
}

I get Errors: undefined reference to 'glewExperimental' and etc. undefined reference to glViewport@16....

Try the code from the github page.