A.Petp=(Pet)c正常执行
B.Petp=(Pet)c编译错误
C.Petp=(Pet)c运行错误
D.以上都不对
第1题:
publicclassPet{privateStringname;publicPet(Stringname){this.name=name;}publicvoidspeak(){System.out.print(name);}}publicclassDogextendsPet{publicDog(Stringname){super(name);}publicvoidspeak(){super.speak();System.out.print(Dog”);}}执行代码Petpet=newDog(京巴”);pet.speak();后输出的内容是哪项?()
A.京巴
B.京巴Dog
C.null
D.Dog京巴
第2题:
有如下程序:
include<iostream>
using namespace std;
class Pet{
char name[10];
public:
Pet(char*name){strcpy(this->name,name);}
const char*getName()const {return name;}
virtual void call()const=0;
};
class Dog:public Pet{
public:
Dog(char*name):Pet(name){}
void call()const{cout<<"汪汪叫":}
};
class Cat:public Pet{
public:
Cat(char*name):Pet(name){}
void call()const{cout<<"喵喵叫";}
};
int main(){
Pet*pet1=new Dog("哈克"),*pet2=new Cat("吉米");
cout<<pet1->getName();pet1->call();cout<<end1;
cout<<pet2->getName();pet2->call();cout<<end1;
return 0;
}
程序的输出结果是______。
第3题:
【单选题】(7-1)定义了Animal类、Cat类和Dog类,则()代码段是正确的。 class Animal{ }; class Cat extends Animal{} class Dog extends Animal{}
A.Dog[] a = new Dog[5]; a[0] = new Cat();
B.Animal a = new Animal[5]; a[0] = new Animal();
C.Dog[]a = new Dog[5]; a[0] = new Animal();
D.Cat[]a = new Cat[5]; a[0] = new Cat();
第4题:
A.Petp=(Pet)c运行错误
B.Petp=(Pet)c编译错误
C.Petp=(Pet)c止常执行
D.以上都不对
第5题:
若有父类Animal及其两个子类Cat、Dog,则以下类型转换正确的有()
A.Cat cat = (Cat)new Animal();
B.Animal a = new Cat(); Cat cat = (Cat) a;
C.Animal animal = new Cat();
D.Animal a = new Dog(); Cat cat = (Cat) a;