vector的push_back对于拷贝构造和赋值操作的调用

http://blog.csdn.net/silyvin/article/details/8985323

对应与CArray，补充一个vector的测试。

class A
{
	int *m_a;
	int bb;
private:
	A();
public:

	A(int n)
	{
		m_a = new int;
		*m_a = n;
	}
	A(A const & _a)
	{
		m_a = 0;
		*this = _a;
	}
	~A()
	{
		delete m_a;
	}
	A &operator=(A const &_a)
	{
		if(this == &_a) return *this;
		if(m_a) delete m_a;	
		m_a = new int;
		*m_a = *_a.m_a;
		return *this;
	}
};

	vector<A> arr;
	A a(1);   
	arr.push_back(a);
	int fenge = 10;
	arr.erase(arr.begin());
	fenge = 9;

push_back时生成对象：

0x0012fb48

0x003ba320

两次调用 copy构造，

然后删除第一个临时对象0x0012fb48

erase时调用第二个对象，也就是在容器中对象的析构函数。

如果将vector换成list，则push_back时仅调用一次copy构造。