CS 117 Spring 2002 Class and Function Reuse derived classes templates

CS 117 Spring 2002 Derived Classes Hanly : Section 6.7 Friedman-Koffman Appendix E

5/3/02 Demo Appointments Next Week –graphics (?) –C++ compared to C, Java –Review for final

Yahtzee using classes Die Dice Scorecard Player Game

Die class Attributes –face value Behavior –roll –print –get value

Dice Attributes –5 Die objects Behavior –roll –print –sum values –test for desired configurations –score as particular configuration

Scorecard Attributes –array of scores –bonus chips for extra yahtzee Behavior –total score –print –score a set of dice in a particular configuration –check to see if a configuration has been scored

Player Attributes –name –scorecard Behavior –take turn –choose configuration to score –get score

Game Attributes –array of players Behavior –play –report result

Reusing classes a class can have member variables of a class type –has-a relationship a class can inherit from another class –is-a relationship

When do you need inheritance you have several classes that share attributes and behavior but differ in minor ways you have a working class that is used by many programs and you need to modify it slightly

base class class base { public: // usual public member functions private: // usual public member functions protected: //variables and functions shared ONLY with derived class }

derived class class derived : public base { public: // additional public member functions private: // additional public member functions }

Template classes and functions functions like swap and sort are needed for many different types array and list classes could be used for many classes

template functions template void swap( T & obj1, T& obj2) { T temp = obj1; obj1 = obj2; obj2 = temp; }

11.3 Template Classes Like functions use templates with classes –template Used before each class definition dummy.h is a definition file for a template class dummy.h is the header file and the definition for a template class named dummy

Template Class Syntax Form:template class className { public: private: };

Object Definitions & Templates Form: class-template-name object; –indexList intList; –type can be any defined data type –class-template-name is name of template class –object is what is created of type dummy numDepend; dummy spouseName; –DummyTest.cpp

Key Issues Notice in the next implementation file a template is a prefix to each function heading Also a dummy :: is used to let the compiler know that the function being defined is a member of a template class –class dummy with parameter T