55 lines
1.2 KiB
C++
55 lines
1.2 KiB
C++
#include <iostream>
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using namespace std;
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class A {
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int a;
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public:
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void setA(int x){ a=x; }
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int getA(){ return a;}
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};
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class B:public A{
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int b;
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public:
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void setB(int x){ b=x; }
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int getB(){ return b;}
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};
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void f1(A a, int x)
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{ a.setA(x); }
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void f2(A *pA, int x)
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{ pA->setA(x); }
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void f3(A &rA, int x)
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{ rA.setA(x); }
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int main(){
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A a1,*pA;
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B b1,*pB;
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a1.setA(1);
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b1.setA(2);
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//把派生类对象赋值给基类对象。
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a1=b1;
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cout<<a1.getA()<<endl;
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cout<<b1.getA()<<endl;
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a1.setA(10);
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cout<<a1.getA()<<endl;
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cout<<b1.getA()<<endl;
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//把派生类对象的地址赋值给基类指针。
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pA=&b1;
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pA->setA(20);
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cout<<pA->getA()<<endl;
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cout<<b1.getA()<<endl;
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//用派生类对象初始化基类对象的引用。
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A &ra=b1;
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ra.setA(30);
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cout<<pA->getA()<<endl;
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cout<<b1.getA()<<endl;
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b1.setA(7);
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cout<<b1.getA()<<endl;
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f1(b1,100);
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cout<<"1111111111"<<endl;
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cout<<b1.getA()<<endl; //7
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f2(&b1,200);
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cout<<b1.getA()<<endl;
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f3(b1,300);
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cout<<b1.getA()<<endl;
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system("pause");
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return 0;
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} |