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];
}
}
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;
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;
or use boost pointer containers
boost::ptr_vector<A> l;
PS: Don't forget A's virtual destructor, as per @Neil Butterworth!
Use an array of shared_ptr, or similar smart pointer. And note that your base class must have a virtual destructor for this code to work correctly.
The best way would be to use smart pointers (Boost shared_ptr) to avoid this kind of things. But if you NEED to have raw pointers I believe this is the way to do it.
来源：https://stackoverflow.com/questions/3447804/vector-of-pointer-to-object-how-to-avoid-memory-leak