PRODUCT  :  Borland C++                           NUMBER  :  1733
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  1/3

    TITLE  :  A functionally complete class (for use with BIDS)




  Using the BIDS libraries requires a functionally complete class.
  That means the class must have the following:

     1.  A default constructor
     2.  A copy constructor
     3.  An assignment operator
     4.  Three comparison operators:
        a. equality,
        b. not equal, and
        c. less than
     5.  A hash value

  Not all of them are necessary, but if your class is a
  functionally complete class, then it can be used with any of the
  BIDS libraries. Thus, making it easier for you to experiment
  with which container would be more efficient for your
  application.

  Here is an example class:

     class MyClass
     {
       protected:
         char *str;
       public:
         // constructors
         MyClass();
         MyClass(const char *s);

         // copy constructor
         MyClass(const MyClass &MC);

         // destructor
         ~MyClass();

         // assignment operator
         MyClass& operator=(const MyClass &MC);

         // equality
         int operator==(const MyClass &MC) const;
         int operator!=(const MyClass &MC) const;

         // comparison for sorted containers













  PRODUCT  :  Borland C++                           NUMBER  :  1733
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  2/3

    TITLE  :  A functionally complete class (for use with BIDS)




         int operator<(const MyClass &MC) const;

         // for hashtables
         unsigned hashValue() const;
     };

     inline MyClass::MyClass()
     {
       str = NULL;
     }

     inline MyClass::MyClass(const char *s)
     {
       str = new char[strlen(s)+1];
       strcpy(str, s);
     }

     inline MyClass::MyClass(const MyClass &MC)
     {
       if (MC.str)
       {
         str = new char[strlen(MC.str)+1];
         strcpy(str, MC.str);
       }
       else
         str = NULL;
     }

     inline MyClass::~MyClass()
     {
       if (str)
         delete str;
     }

     inline MyClass& MyClass::operator =(const MyClass &MC)
     {
       if (str != NULL)
         delete str;
       if (MC.str)
       {
         str = new char[strlen(MC.str)+1];
         strcpy(str, MC.str);
       }













  PRODUCT  :  Borland C++                           NUMBER  :  1733
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  3/3

    TITLE  :  A functionally complete class (for use with BIDS)




       else
         str = NULL;
       return *this;
     }

     inline int MyClass::operator ==(const MyClass &MC) const
     {
       return strcmp(str, MC.str) == 0;
     }

     inline int MyClass::operator !=(const MyClass &MC) const
     {
       return !(*this == MC);
     }

     inline int MyClass::operator <(const MyClass &MC) const
     {
       return strcmp(str, MC.str) < 0;
     }

     inline unsigned MyClass::hashValue() const
     {
       unsigned Hash = 0;
       if (str == NULL)
         return 0;
       for (int i=0; i<strlen(str); i++)
         Hash += unsigned(str[i]);
       return Hash;
     }


  If your class does not require usage of the hash tables, then
  the hashValue() member function can simply return 1.




  DISCLAIMER: You have the right to use this technical information
  subject to the terms of the No-Nonsense License Statement that
  you received with the Borland product to which this information
  pertains.