指向对象的指针向量 - 如何避免内存泄漏?-C/C++问题

vector of pointer to object - how to avoid memory leak?(指向对象的指针向量 - 如何避免内存泄漏?)

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问题描述

我们通常如何处理一个元素是指向对象的指针的向量?我的具体问题是下面提供的代码末尾的注释.谢谢.

How do we ususaly deal with a vector whose elements are pointers to object? My specific question is the comment at the end of the code supplied below. Thanks.

class A
{
 public:
 virtual int play() = 0 ; 
};

class B : public A 
{
public:
 int play() {cout << "play in B " << endl;};

};

class C : public A 
{
public:
 int play() {cout << "play in C " << endl;};

};


int main()
{

    vector<A *> l;
    l.push_back(new B());
    l.push_back(new C());

    for(int i = 0 ; i < l.size();i++)
    {
            l[i]->play();
    }

    //Do i have to do this to avoid memory leak? It is akward. Any better way to do this? 
    for(int i = 0 ; i < l.size();i++)
    {
            delete l[i];
    }

  }

推荐答案

是的，您必须这样做才能避免内存泄漏.更好的方法是制作一个共享指针向量(boost、C++TR1、C++0x、)

Yes, you have to do that to avoid memory leak. The better ways to do that are to make a vector of shared pointers (boost, C++TR1, C++0x, )

 std::vector<std::tr1::shared_ptr<A> > l;

或唯一指针向量 (C++0x) 如果对象实际上不是在此容器和其他对象之间共享

or vector of unique pointers (C++0x) if the objects are not actually shared between this container and something else

 std::vector<std::unique_ptr<A>> l;

或使用 boost 指针容器

  boost::ptr_vector<A> l;

PS:不要忘记 A 的虚拟析构函数，正如@Neil Butterworth 所说！

PS: Don't forget A's virtual destructor, as per @Neil Butterworth!

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