理解复制构造和赋值操作符之间的区别

类能报告对象的创建、销毁、赋值以及每个对象一个识别号（代码来源于C++沉思录）

#include 

class Test{
public:
	Test();
	Test(const Test&);
	Test& operator=(const Test&);
	~Test();
private:
	static int count;
	int id;
};

int Test::count = 0;
Test::Test(){
	id = ++count;
	std::cout << "Test " << id
		<< " default constructor\n"; 
}
Test::Test(const Test& t){
	id = ++count;
	std:: cout << "Test " << id
			<< " copied from " << t.id << std::endl;
}
Test& Test:: operator=(const Test& t){
	std:: cout << "Test " << id
		<< " assigned from " << t.id << std::endl;
}
Test::~Test(){
	std::cout << "Test " << id << " destroyed" << std::endl;
}

int main()
{
	Test s;
	Test t(s);
	s = t;
	
    return 0;
}