创建不同子类的实例的向量 [英] Making a vector of instances of different subclasses

问题描述

尝试搜索，没有返回（i ithink）。

Tried searching, nothing returns( i ithink).

是否可以创建抽象类的向量？

Is it possible to make a vector of an abstract class?

例如，我有超级类Unit。

For example, I have the super class Unit.

我有子类兵士，车辆和轰炸机。

And I Have the subclasses soldier, vehicle, and bomber.

然而，我想要任何子类的一个向量中的实例，例如向量UnitList可以持有士兵和车辆的实例？

However I would want ever instance of any subclass in one vector, e.g. the vector UnitList can hold instances of both soldier and vehicle?

这是可能吗？
我使用C ++如果它有帮助。

Is this possible? I'm using C++ if it helps.

推荐答案

是的，但你需要使用指针或智能指针（我会用这个）。

Yes, but you'll need to use either pointers or smart pointers (I'd go with this).

struct X
{
    virtual ~X() {}  //<--- as pointed out in the comments
                     // a virtual destructor is required
                     // for correct deletion
    virtual void foo() = 0;
};
struct Y : X
{
    virtual void foo() { }
};

int main()
{
    std::vector<X*> a;
    a.push_back(new Y);
    a[0]->foo();
    for ( int i = 0 ; i < a.size() ; i++ )
        delete a[i];
    return 0;
}

不要忘记删除已分配的内存。

Don't forget to delete the allocated memory.

假设 std :: vector< X> 。这是非法的，因为：

Assume std::vector<X>. This is illegal because:

1. 如果你想用一些元素初始化你的向量，向量在连续内存中内部存储对象。

1. If you want to initialize your vector with some number of elements, the allocation would fail. A vector stores objects internally in continuous memory. A preallocation would fail because it would mean it needed to create objects, which can't be done for abstract classes.

即使你可以，或者基础

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