title: How to check the Version of the OpenGL on Windows 7kl
body: <p>I am using the Windows 7. I am programming using the OpenGL on it. But I found that there are some features I can use. So I want to check the version of the OpenGL on my system.
  I use the code below to check it</p>
  
  <pre><code>const char* version = (const char*)glGetString(GL_VERSION); 
  </code></pre>
  
  <p>But I get a null pointer. And if I want to upgrade my OpenGL, what should I do?</p>