面向对象的程序设计.ppt

1、C+面向对象程序设计Object-Oriented Programming in C+,山东工商学院.计算机科学与技术学院 刘培强 ,2010-2011-01 电信08 计科09,1/44,Chap.1 Object-Oriented Programming,2/44,Content,1.1 Object-Oriented and Procedural Programming 1.2 Classes and Abstract Data Types 1.3 The Client/Server Model and Message Passing 1.4 Inheritance and Polymo

2、rphism 1.5 Interfaces and Components 1.6 Template,3/44,1.1 Object-Oriented and Procedural Programming,4/44,程序设计范型 ( Programming Paradigms/style ) 程序设计范型程序设计时所采用的基本方式模型。它决定了在程序设计时的思维方式及所采用的工具，它受应用领域的约束，以某一类程序设计语言为基础。 程序设计风格（Programming Styles）通常由思维方式和语言支持所决定，而不同的领域要求的思维方式不同，因而程序设计风格不同，对语言的支持要求也不同。,5/

3、44,Procedural Programming(面向过程编程),Decide which procedures you want; (程序设计的核心) use the best algorithms you can find.（过程的内涵）,以功能为中心，基于功能分解的程序设计范型,程序可以被看作为函数调用序列(图中没有画出三级函数),main program data,Procedure 1,Procedure 2,Procedure 3,6/44,Procedural Programming,Procedural programming is associated with a des

4、ign technique knows as top-down design（自顶向下）.,Build an automobile,Problem decomposition 问题分解,7/44,Procedural Programming,In top-down design, a problem is associated with a procedure.,void buildC() void inspect() int main() buildC(); buildE(); buildD(); assemble(); inspect(); ,8/44,Object-Oriented Pr

5、ogramming (OOP),动物界,软体动物门,脊索动物门,爬行纲,哺乳纲,食肉目,灵长目,人科,人属,人种,界,门,纲,目,科,属,种,角龙科,林奈物种继承层次图,9/44,Object-Oriented Programming,Decide which classes you want; provide a full set of operations for each class; make commonality(共性) explicit by using inheritance(继承).,10/44,Object-Oriented Programming,Class(类) 是对一

6、组类似事物的共同属性和行为特征的抽象描述. Objects(对象) in a class share properties, features, or attributes. In C+, these attributes are called data members(数据成员). A class has actions or processes associated with it. Objects in a class share these actions. In C+, these actions are called function members(成员函数) or method

7、s(方法).,11/44,Object-Oriented Programming,Relationships(关系),Human,Animal,is a,Mary Leakey,instance of,12/44,1.2 Classes and Abstract Data Types,13/44,Information Hiding（信息隐蔽）,The implementation is hidden from the user, whereas the interface is exposed(暴露) to the user. In an object-oriented language,

8、a class is a module that supports information hiding. In a C+ class, we can use keywords such as public and private to control access （存取） to the classs properties and operations.,14/44,Encapsulation（封装）,The standard mechanism for procedural programming of data manipulation （操作） is passing arguments

9、 to and returning a value from a function. In object-oriented programming, data and the procedures to manipulate the data can be encapsulated （封装） or contained within a class. A typical role of the classs encapsulated data members is to support its encapsulated methods.,15/44,Abstract Data Types（抽象数

10、据类型，ADT）,ADT: exposes public interface, hides implementation details. ADT: 值集 操作集,class RECT private: double top, left; double bottom, right; public: void init( double, double, double, double ); void draw(); void move( double x, double y); ;,优点： 模块化程度高 密封性可保证数据完整 实现部分可独立更换,16/44,Class（类）,Class is a

11、user-defined type(用户自定义类型). A type is a concrete representation of a concept in application domain(领域). We design a new type to provide a definition of a concept that has no direct counterpart(复本) among the built-in(内建、内置) types.,17/44,1.3 Client/Server Model,A client requests services from a Server

12、 object by invoking one of its methods, which is characterized as sending a message to the object.,Client,Server,GET http:/server/,C,S,in C: Server S; int ret = S.GET ( “http:/server/” );,18/44,1.4 Inheritance and Polymorphism,Inheritance is a convenient and efficient way to specialize (特化) or exten

13、d(扩展) a parent class by creating a child class.,Base class,Derived class,Inheritance,Super/Parent class,Subclass,is a,19/44,1.4 Inheritance and Polymorphism,Inheritance allows the designer to combine features of classes in a common parent class. Inheritance supports a form of code reuse（代码重用）.,Infor

14、mationDialog,MenuWindow,DialogWindow,EditWindow,QuestionDialog,Window,Inheritance hierarchy,20/44,1.4 Inheritance and Polymorphism（多态）,single inheritance(单继承) : a child class has exactly one direct parent. multiple inheritance(多继承) : a child class may have multiple direct parents.,Manager,Temporary,

15、Consultant,Worker,21/44,1.4 Inheritance and Polymorphism,Polymorphism: In an object-oriented language, there can be many methods with the same signature.,静态绑定： Ex. int i1 = 10 5; int add(int, int); double d2 = 10.2 5.0; double add(double, double);,22/44,1.4 Inheritance and Polymorphism,Its common fo

16、r each class in the hierarchy to provide its own appropriate version of a polymorphic method. 动态绑定： Ex.,23/44,1.5 Interface and Components(接口和组件),A classs interface consists of what it exposes. Abstract base class(抽象类),24/44,有时，即使是用有向无环图(directed acyclic graph)也不足以组织一个程序中的概念，因为有些概念看上去是固有地相互依赖着。这时，我们

17、应当试着将这样的环形依赖限制在程序的局部，以免使它们影响整个程序的结构。 化解依赖图最好的工具之一，是明确地分离接口与实现，C+的抽象类（Abstract Classes）就是这样的工具。,Abstract base class(抽象类),25/44,1.5 Interface and Components(接口和组件),C+ uses abstract base class(抽象类) to specify an interface as a collection of public, high-level methods.,class stdFile public: virtual void

18、 Open(const char* name, int mode) = 0; virtual void Close() = 0; virtual void Rewind() = 0; ;,26/44,1.5 Interface and Components(接口和组件),A software component is a pre-built part that can be combined with other such parts to build an application (应用程序). A component is placed in a container （容器）, a software construct designed to integrate components by handling communications among them. A software component is typically delivered as a binary file and, therefore, its contents are hidden from the programmer who uses it.,27/44,