问题描述:
下面是给出的基类Animal声明和main()函数。
[cpp] view plaincopyprint?
- <strong><span style="font-family:KaiTi_GB2312;font-size:18px;color:#ff6666;">class Animal
- {
- public:
- virtual void cry()
- {
- cout<<"不知哪种动物,让我如何学叫?"<<endl;
- }
- };
- int main( ){
- Animal *p;
- p = new Animal();
- p->cry();
- Mouse m1("Jerry",‘m‘);
- p=&m1;
- p->cry();
- Mouse m2("Jemmy",‘f‘);
- p=&m2;
- p->cry();
- Cat c1("Tom");
- p=&c1;
- p->cry();
- Dog d1("Droopy");
- p=&d1;
- p->cry();
- Giraffe g1("Gill",‘m‘);
- p=&g1;
- p->cry();
- return 0;
- }</span></strong>
<strong><span style="font-family:KaiTi_GB2312;font-size:18px;color:#ff6666;">class Animal { public: virtual void cry() { cout<<"不知哪种动物,让我如何学叫?"<<endl; } }; int main( ){ Animal *p; p = new Animal(); p->cry(); Mouse m1("Jerry",'m'); p=&m1; p->cry(); Mouse m2("Jemmy",'f'); p=&m2; p->cry(); Cat c1("Tom"); p=&c1; p->cry(); Dog d1("Droopy"); p=&d1; p->cry(); Giraffe g1("Gill",'m'); p=&g1; p->cry(); return 0; }</span></strong>
程序的运行结果将是:
2、显然,Animal设计为抽象类更合适,Animal不需要能够实例化,是专门作基类使用的。改造程序,使Animal设计为抽象类,这时main()函数中p = new Animal();将出错,将此行删除。
代码:
#include <iostream> #include <cstring> using namespace std; class Animal{ public: virtual void cry()=0; }; class Mouse:public Animal{ private: string name; char sex; public: Mouse(string s,char x):name(s),sex(x){} void cry(){ cout<<"我叫"<<name<<",我是一只"<<(sex=='m'?"公":"母")<<"老鼠,我的叫声是:吱吱吱!\n"; } }; class Cat:public Animal{ private: string name; public: Cat(string s):name(s){} void cry(){ cout<<"我叫"<<name<<",我是一只猫,我的叫声是:喵喵喵!\n"; } }; class Dog:public Animal{ private: string name; public: Dog(string s):name(s){} void cry(){ cout<<"我叫"<<name<<",我是一只狗,我的叫声是:汪汪汪!\n"; } }; class Giraffe:public Animal{ private: string name; char sex; public: Giraffe(string s,char x):name(s),sex(x){} void cry(){ cout<<"我叫"<<name<<",我是一只"<<(sex=='m'?"公":"母")<<"长颈鹿,我的脖子太长,发不出声音来!\n"; } }; int main( ){ Animal *p; Mouse m1("Jerry",'m'); p=&m1; p->cry(); Mouse m2("Jemmy",'f'); p=&m2; p->cry(); Cat c1("Tom"); p=&c1; p->cry(); Dog d1("Droopy"); p=&d1; p->cry(); Giraffe g1("Gill",'m'); p=&g1; p->cry(); return 0; }
运行结果:
时间: 2024-10-28 09:59:29