C++继承特性

时间 2019-12-09

标签 c++ 继承特性栏目 C&C++ 繁體版

原文原文链接

1. 子类不声明构造函数

#include <iostream>
class Uncopyable {
public:
  Uncopyable();
  ~Uncopyable() {}
  Uncopyable(const Uncopyable&);
  Uncopyable& operator=(const Uncopyable&);
};

Uncopyable::Uncopyable() {
  std::cout << "inherit default constructor\n";
} 

Uncopyable::Uncopyable(const Uncopyable&) {
  std::cout << "inherit copy constructor\n";
}

Uncopyable& Uncopyable::operator=(const Uncopyable&) {
  std::cout << "inherit copy asigment\n";
  return *this;
}

class HomeForSale: private Uncopyable {
};

int main() {
  HomeForSale s1;
  HomeForSale s2(s1);
}

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输出ios

inherit default constructor
inherit copy constructor
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子类调用相应的父类构造函数（counterpart）bash

2.子类声明构造函数

#include <iostream>
class Uncopyable {
public:
  Uncopyable();
  ~Uncopyable() {}
  Uncopyable(const Uncopyable&);
  Uncopyable& operator=(const Uncopyable&);
};

Uncopyable::Uncopyable() {
  std::cout << "inherit default constructor\n";
} 

Uncopyable::Uncopyable(const Uncopyable&) {
  std::cout << "inherit copy constructor\n";
}

Uncopyable& Uncopyable::operator=(const Uncopyable&) {
  std::cout << "inherit copy asigment\n";
  return *this;
}

class HomeForSale: private Uncopyable {
  public:
  HomeForSale();
  HomeForSale(const HomeForSale&);
};

HomeForSale::HomeForSale() {
  std::cout << "HomeForSale default constructor\n";
}

HomeForSale::HomeForSale(const HomeForSale&) {
  std::cout << "HomeForSale copy constructor\n";
}

int main() {
  HomeForSale s1;
  HomeForSale s2(s1);
}

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输出函数

inherit default constructor
HomeForSale default constructor
inherit default constructor
HomeForSale copy constructor
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子类调用父类默认构造函数ui