title: What does &operator mean in overloading
body: <p>I am reading a C++ book.
  The program tries to make a vector of objects.
  Here is the part I do not understand</p>
  
  <pre><code>class X {
  public:
      X();
      X(int m) {
          temp = x;
      }
  
      int temp;
  
  
      X &amp;operator =(int z) {
          temp = z;
          return *this;
      }
  
  private :
      //            Some functions here
  }
  </code></pre>
  
  <p>What does above line mean?
  Is this some sort of overloading?
  Then how?</p>