title: unresolved external symbol "private: static int Math::result"
body: <p>this is my class definition:</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  using namespace std;
  
  class Math
  {
  private:
      static int result;
  
  public:
      static int add( int a , int b)
      {
          result = a + b ;
          return result;
      };
  };
  </code></pre>
  
  <hr>
  
  <p>this is the main:</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include "Amin.cpp"
  
  using namespace std;
  
  int main()
  {
      Math::add(2,3);
  }
  </code></pre>
  
  <p>and i got these errors in visual studio:</p>
  
  <p>error LNK2001: unresolved external symbol "private: static int Math::result" 
  error LNK1120: 1 unresolved externals   </p>
  
  <p>best regards</p>