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

先上笔记内容吧：

这次上课的内容有关

1. 构造函数
2. 析构函数
3. 运算符重载
4. return * this

　　内容很细，大家好好回顾笔记再照应程序复习吧　:)

#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 Functioni = 18;cout << "Integer (Integer & c)" << endl;
}Integer::Integer (int j) : i(j) {   //Copy Constructer Functioncout << "Integer (int j)" << endl;
}Integer::~Integer () {              //Destructer Functioncout << "~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;
}

下面这个程序是有关运算符重载

通过　log print 可以跟踪观察到析构的顺序

同时还有引用返回、友元函数的例子

 

#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 Functioni = 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 Functioni = 18;cout << "Integer (Integer & c)" << endl;
}Integer::Integer (int j) : i(j) {   //Copy Constructer Functioncout << "Integer (int j)" << ' ' << j << endl;
}Integer::~Integer () {              //Destructer Functioncout << "~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;
}

 

 接下来运算符重载作一些附加说明

• =
• &
• ,

这三个运算符可以直接使用

运算符重载的时候，如果既有 成员函数，又有全局函数， 优先(?)　　

eg.

++i (前加) Integer & operator ++ ()
i++ (后加) Integer & operator ++ (int)
括号中的 int 仅仅表示后加，无其他含义

 

下面的这个例子可以帮助大家更好的理解

#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();Integer & operator ++ ();Integer operator ++ (int);const Integer & operator = (const Integer & in);friend const Integer operator + (const Integer & lhs, const Integer & rhs);
};Integer & Integer::operator ++ () {++i;return *this;
}Integer Integer::operator ++ (int) {Integer temp (this->i);++temp.i;return temp;
}const Integer & Integer::operator = (const Integer & in) {  //Member Functioni = in.i;//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 Functioni = 18;cout << "Integer (Integer & c)" << endl;
}Integer::Integer (int j) : i(j) {   //Copy Constructer Functioncout << "Integer (int j)" << ' ' << j << endl;
}Integer::~Integer () {              //Destructer Functioncout << "~Integer () " << ' ' << i << endl;
}int main (){Integer b(8), a;cout << b.geti () << "," << a.geti () << endl;a = ++b;cout << b.geti () << "," << a.geti () << endl;a = b++;cout << b.geti () << "," << a.geti () << endl;return 0;
}