title: Differences where declaring inline keyword
body: <pre><code>inline void foo();
  
  int main() {
      foo(); return 0;
  }
  
  void foo(){
  }
  </code></pre>
  
  <p>Is there any difference if setting <code>foo</code>'s declaration as <code>inline</code> and not <code>foo</code>'s definition? How about the opposite?  How about marking them both as <code>inline</code>?</p>