copyconstructor.cpp

ThinkingC++中文版

//: C14:CopyConstructor.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
// Correctly creating the copy-constructor
#include <iostream>
using namespace std;

class Parent {
  int i;
public:
  Parent() : i(0) 
  { 
	  cout << "Parent()\n"; 
  }

  Parent(int ii) : i(ii) 
  {
      cout << "Parent(int ii)\n";
  }
  Parent(const Parent& b) : i(b.i) 
  {
      cout << "Parent(const Parent&)\n";
  }

  friend ostream&   operator<<(ostream& os, const Parent& b) 
  {
      return os << "Parent: " << b.i << endl;
  }
};

class Member {
  int i;
public:
  Member(int ii) : i(ii) 
  {
    cout << "Member(int ii)\n";
  }
  Member(const Member& m) : i(m.i) 
  {
    cout << "Member(const Member&)\n";
  }
  friend ostream& operator<<(ostream& os, const Member& m) 
  {
    return os << "Member: " << m.i << endl;
  }
};

class Child : public Parent {
  int i;
  Member m;
public:
  Child(int ii) : Parent(ii), i(ii), m(ii) 
  {
    cout << "Child(int ii)\n";
  }

  Child(const Child& c) : Parent(c),i(c.i), m(c.m) 
  {
  }

  friend ostream& operator<<(ostream& os, const Child& c)
  {
    return os << (Parent&)c << c.m << "Child: " << c.i << endl;
  }
};

void main() 
{
  Child c(2);
  cout << "calling copy-constructor: " << endl;
  Child c2 = c; // Calls copy-constructor
  cout << "values in c2:\n" << c2;
} ///:~