面向对象程序设计-C++ Default constructor & Copy constructor& Destructor & Operator Overloading【第九次上课笔记】

#include <iostream>

using namespace std;

class Integer {
public:
    int i;
    int geti () const {return this->i;}
    void seti (int i) {this->i = i;}
    Integer(int j = 0);
    Integer(Integer & c);
    ~Integer();
};

Integer::Integer (Integer & c) {    //Constructer Function
    i = 18;
    cout << "Integer (Integer & c)" << endl;
}

Integer::Integer (int j) : i(j) {   //Copy Constructer Function
    cout << "Integer (int j)" << endl;
}

Integer::~Integer () {              //Destructer Function
    cout << "~Integer () " << endl;
}

const Integer & fun (const Integer & in) {
    cout << in.geti () << endl;
    return in;
}

int main (){

    Integer b(8);
    fun(b).geti();
    Integer a(b);

    return 0;
}

#include <iostream>

using namespace std;

class Integer {
private:
    int i;
public:
    int geti () const {return this->i;}
    void seti (int i) {this->i = i;}
    Integer(int j = 0);
    Integer(Integer & c);
    ~Integer();

    const Integer & operator = (const Integer & in);
    friend const Integer operator + (const Integer & lhs, const Integer & rhs);
};

const Integer & Integer::operator = (const Integer & in) {  //Member Function
    i = in.i + 50;
    //return in;
    return *this;
}

const Integer operator + (const Integer & lhs, const Integer & rhs) { //全局函数
    Integer out;
    out.i = lhs.i + rhs.i;
    return out;
}

Integer::Integer (Integer & c) {    //Constructer Function
    i = 18;
    cout << "Integer (Integer & c)" << endl;
}

Integer::Integer (int j) : i(j) {   //Copy Constructer Function
    cout << "Integer (int j)" << ‘ ‘ << j << endl;
}

Integer::~Integer () {              //Destructer Function
    cout << "~Integer () " << ‘ ‘ << i << endl;
}

int main (){

    Integer b(8), a, c, d;
    cout << "a.geti()" << a.geti() << endl;
    d = c = a = b;
    cout << "a.geti()" << a.geti() << endl;
    cout << "c.geti()" << c.geti() << endl;
    cout << "d.geti()" << d.geti() << endl;

    d = a + b;
    cout << "d.geti()" << d.geti() << endl;

    return 0;
}