title: Double Colon confusions
body: <p>Why can I use double colons in functions and classes not defined but I can't use in variables ??</p>
  
  <p>Example:</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  using namespace std;
  
  class Person{
  
      public:
          int age;
          string name();
  };
  
  int Person::age = 10; //It outputs an error
  
  string Person::name(){ //It doesn't
      return "n";
  }
  </code></pre>