C++STL中vector容器的使用

#include <iOStream>
#include <vector>
using namespace std;
class Value
{
public:
	Value()
	{
		cout << "Value()"<< endl;
	}
	~Value()
	{
		cout << "~Value()" << endl;
	}
};
void Vector_user()
{
	vector<Value> vec;
	//vec.resize(10);
	vec.reserve(10);
	cout << vec.capacity()<< endl;
	cout << vec.size()<< endl;
}
int main()
{
	Vector_user();
	return 0;
}

#include <iostream>
#include <vector>
using namespace std;
class Value
{
public:
	Value()
	{
		cout << "Value()"<< endl;
	}
	~Value()
	{
		cout << "~Value()" << endl;
	}
};
void Vector_user()
{
	vector<Value> vec;
	vec.resize(10);
	//vec.reserve(10);
	cout << vec.capacity()<< endl;
	cout << vec.size()<< endl;
}
int main()
{
	Vector_user();
	return 0;
}

#include <iostream>
#include <vector>
using namespace std;
class Object
{
private:
	int val;
public:
	Object(int x = 0):val(x)
	{
		cout << "Object(int x)"<< endl;
	}
	Object(const Object& src): val(src.val)
	{
		cout << "Object(const Object& src)" << endl;
	}
	Object(Object&& src) : val(src.val)
	{
		cout << "Object(Object&& src)" << endl;
	}
	Object& operator=(const Object& src)
	{
		val = src.val;
		cout << "=" << endl;
		return *this;
	}
	Object& operator=(Object&& src)
	{
		val = src.val;
		cout << "=&" << endl;
		return *this;
	}
	~Object()
	{
		cout << "~Object()" << endl;
	}
};
void fun()
{
	std::vector<Object> vcobj;
	vcobj.reserve(5);
	vcobj.push_back(10);
	//vcobj.push_back(Object(10));
}
int main()
{
	fun();
	return 0;
}

void fun()
{
	std::vector<Object> vcobj;
	vcobj.reserve(5);
	vcobj.emplace_back(10);
}

void fun()
{
	std::vector<Object> vcobj;
	vcobj.reserve(5);
	vcobj.emplace_back(Object(10));
}

void fun()
{
	std::vector<Object> vcobj;
	vcobj.reserve(5);
	Object obj(10);
	vcobj.emplace_back(obj);
}

template<class T, class ...Arg>
void Make(T* p, Arg... arg)
{
	new(p) T(std::forward<Arg...>(arg)...);
}
int main()
{
	//1.开辟空间
	Object* p = (Object*)malloc(sizeof(Object));
	//2.在p指向的地址空间调用构造Object(10)
	Make(p, 10);
	//3.释放空间并调用析构函数
	delete p;
	return 0;
}