C初探创建和使用对象.pptVIP

《面向对象程序设计》 中国科技大学计算机系 马建辉 第二章 C++初探:创建和使用对象 面向对象程序设计(C++) 2.1 概述 This chapter explains key differences between C and C++, and takes you through three essential C++ features: Type safety (类型安全性) Classes (类：抽象、封装、多态性等) Templates (模板) Also covered are IOStreams and the free store operators new and delete. 2.1 概述(cont.) History Changes to C subset IOStreams new and delete Objects Templates 2.2 C++的历史 Bjarne Stroustrup, Bell Labs (1980s) C with Classes Add objects to C Leverage C’s efficiency(效率), portability(轻巧性), availability(可用性) ANSI Committee, 1991 ISO Standard, July 1998 2.3 对C子集的某些改进 Motivated mostly by type safety a is char, not int (@c) a is const char*, not char* (@c) f() is the same as f(void) 而在C中等同于参数个数不确定的函数 const integers can be used as array dimensions 常量在C++中通常是一个符号表中的条目；而在C中是一个变量。 Structure tags are type names 2.4 对C的扩展 Abstract (抽象) Encapsulation (封装) Access Control(Public,Private,Protected) Friends(友元)：允许友元破坏封装性 Inheritance (继承) Virtual Function (多态性) Later Binding (晚绑定) Overloading (重载) -- 允许函数名和运算符重载 Template (模板) 2.5 C++的输入输出:IOStreams初探 2.6 new and delete 运算符 Replacement for malloc/free int* ip = new int(7); delete ip; int* iap = new int[10]; delete [] iap; Compile-time operators --- Calculate size of objects for you Automatic initialization cleanup 2.7 对象(Object)概述 Based on Classes structs with member functions Always have an associated object Improved support for information hiding private, protected keywords Automatic initialization/cleanup(构造和析构函数) 2.7.1 例：Class Stack 2.8 Templates(模板：参数化的类) Support generic programming Ideal for containers Logic is independent from contained objects You write the template code once Compiler generates versions on demand 例：通用栈模板 2.9 小结:A First Look at C++ C++ emphasizes type safety IOStreams provide type-safe I/O new and delete provide safe heap management Classes are l