vector assignment

Between vector assignment can not be used memcpy_s, it will lead to memory errors of the original variables (guess).

They could use recycled won assign assignment methods, methods assign higher efficiency.

static vector<string> vec_test(1000000, "无力的反垄断的积分辣豆腐");

int main()
{
	vector<string> v1;
	vector<string> v2;
	vector<string> v3;
	
	int t1,t2;

	t1 = GetTickCount();
	for (int i = 0; i < 1000000; ++i)
	{
		v1.push_back(vec_test[i]);
	}
	t2 = GetTickCount();
	cout << t2 - t1 << endl;

	t1 = GetTickCount();
	vector<string>::iterator itr;
	for (itr = vec_test.begin(); itr != vec_test.end(); ++itr)
	{
		v2.push_back(*itr);
	}
	t2 = GetTickCount();
	cout << t2 - t1 << endl;

	t1 = GetTickCount();
	v3.assign(vec_test.begin (), vec_test.end ());
	t2 = GetTickCount();
	cout << t2 - t1 << endl;
}