744: Mainline

To determine whether a list has been traversed completely, you define endp. The endp predicate is easy to define, because, when you work on a pointer with the negation operation, the result is 1, of type int, if the pointer is the null pointer; otherwise, the result is 0, of type int:

class header { 
  public: 
    link *first_link_pointer; 
    link *current_link_pointer; 
    header ( ) { 
      first_link_pointer = NULL; 
      current_link_pointer = first_link_pointer; 
    } 
    ... 
    int endp ( ) {                     
      return ! current_link_pointer;   
    }                                  
    ... 
};