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