class Derived Base Derived Base Discount Sale Sale

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확장 형 호환 · “class Derived : Base” 이면 - Derived 클래스 객체는 Base

확장 형 호환 · “class Derived : Base” 이면 - Derived 클래스 객체는 Base 클래스 객체에 할 당 가능 - 역은 성립하지 않음! · 예: - Discount. Sale 은 Sale 이지만, 역은 성립하지 않 는다 Copyright © 2006 Pearson Addison-Wesley. All rights reserved. 15 -9

확장 형 호환의 예 · class Pet { public: string name; virtual void print()

확장 형 호환의 예 · class Pet { public: string name; virtual void print() const; }; class Dog : public Pet { public: string breed; virtual void print() const; }; Copyright © 2006 Pearson Addison-Wesley. All rights reserved. 15 -10

Pet 클래스와 Dog 클래스 · 다음의 선언을 고려: Dog vdog; Pet vpet; · 멤버

Pet 클래스와 Dog 클래스 · 다음의 선언을 고려: Dog vdog; Pet vpet; · 멤버 변수 name과 breed는 public! - 설명을 위한 예제! Copyright © 2006 Pearson Addison-Wesley. All rights reserved. 15 -11

Pet 클래스와 Dog 클래스 사용 · dog "is a" pet: - vdog. name =

Pet 클래스와 Dog 클래스 사용 · dog "is a" pet: - vdog. name = "Tiny"; vdog. breed = "Great Dane"; vpet = vdog; - 위의 예는 허용됨 · 부모 형에 할당 가능 - 역은 성립되지 않음 - A pet "is not a" dog Copyright © 2006 Pearson Addison-Wesley. All rights reserved. 15 -12

슬라이스 문제 (Slicing Problem) · vpet에 할당되면서 breed가 손실됨! - cout << vpet. breed;

슬라이스 문제 (Slicing Problem) · vpet에 할당되면서 breed가 손실됨! - cout << vpet. breed; · ERROR msg! - 슬라이스 문제 · Dog 형이 Pet 형으로 변환 - Dog 형 고유의 속성을 없어짐 Copyright © 2006 Pearson Addison-Wesley. All rights reserved. 15 -13

슬라이스 문제 예 (1/2) · Pet *ppet; Dog *pdog; pdog = new Dog; pdog->name

슬라이스 문제 예 (1/2) · Pet *ppet; Dog *pdog; pdog = new Dog; pdog->name = "Tiny"; pdog->breed = "Great Dane"; ppet = pdog; · ppet으로 breed에 접근이 불가능: cout << ppet->breed; Copyright © 2006 Pearson Addison-Wesley. All rights reserved. //ILLEGAL! 15 -15

변환 · 다음을 고려: Pet vpet; Dog vdog; … vdog = static_cast<Dog>(vpet); //ILLEGAL! ·

변환 · 다음을 고려: Pet vpet; Dog vdog; … vdog = static_cast<Dog>(vpet); //ILLEGAL! · 다음은 허용됨: vpet = vdog; // Legal! vpet = static_cast<Pet>(vdog); //Also legal! · 확대변환(upcasting) is OK - 자손 형을 조상형으로 Copyright © 2006 Pearson Addison-Wesley. All rights reserved. 15 -18

Derived Class Derived class and Base class baseclassDerived Class Derived class and Base class baseclass
Super Base class class Sub Derived class classSuper Base class class Sub Derived class class
3 1 Class Base Class Derived Base int3 1 Class Base Class Derived Base int
sale by standard specification sale by standard salesale by standard specification sale by standard sale
sale by standard specification sale by standard salesale by standard specification sale by standard sale
Medical Discount Cards a k a discount healthMedical Discount Cards a k a discount health
Discount Sales Tax Tipping Commission Discount is anDiscount Sales Tax Tipping Commission Discount is an
Sales Tax and Discount Sales tax and discountSales Tax and Discount Sales tax and discount
National Discount Broker Site Compromised National Discount BrokersNational Discount Broker Site Compromised National Discount Brokers
Discount Evaluation Evaluating with experts Discount Evaluation TechniquesDiscount Evaluation Evaluating with experts Discount Evaluation Techniques
Fundamental Derived Positions Fundamental derived Positions Fundamental derivedFundamental Derived Positions Fundamental derived Positions Fundamental derived
basis class derived class Basis class Parent classbasis class derived class Basis class Parent class
Class class Class for Name Class Class classClass class Class for Name Class Class class
Discount and Sale Price Sometimes stores have SALESDiscount and Sale Price Sometimes stores have SALES
Algebra Ratios Rates Proportions Percents Discount and SaleAlgebra Ratios Rates Proportions Percents Discount and Sale
Public class derivedcl public basecl Base Derived privatePublic class derivedcl public basecl Base Derived private
Polymorphism I 1 Definition Base Class Number DerivedPolymorphism I 1 Definition Base Class Number Derived
Abstract Class Abstract class A base class thatAbstract Class Abstract class A base class that
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