title: ampersand (&) at the end of variable etc
body: <p>I am a C++ noob and i've a problem of understanding c++ syntax in a code. Now I am quite confused.</p>
  
  <pre><code>class date
  {
  private:
  int day, month, year;
  int correct_date( void );
  public:
  void set_date( int d, int m, int y );
  void actual( void );
  void print( void );
  void inc( void );
  friend int date_ok( const date&amp; );
  };
  </code></pre>
  
  <p>Regarding to the '&amp;' character, I understand its general usage as a reference, address and logical operator...</p>
  
  <p>for example int *Y = &amp;X   </p>
  
  <p>What is the meaning of an &amp; operator at end of parameter?</p>
  
  <pre><code>friend int date_ok( const date&amp; );
  </code></pre>
  
  <p>Thanks</p>
  
  <p><strong>edit:</strong></p>
  
  <p>Thanks for the answers. 
  If I have understood this correctly, the variable name was simply omitted because it is just a prototype. For the prototype I don't need the variable name, it's optional. Is that correct?</p>
  
  <p>However, for the definition of the function I definitely need the variable name, right?</p>