在C ++中的instanceof等价物 [英] instanceof equivalent in C++

问题描述

我正在用C ++创建一个二维游戏，它使用由瓷砖制成的等级。世界级有一个 add（WorldObject * o）函数，它既可以接受磁贴，也可以接受敌人等实体。 Tile 和实体类都派生自 WorldObject 。在每种情况下，都应将对象添加到实体列表中;但如果它是一个图块，它也应该被添加到 tiles 列表中。

I'm creating a 2D game in C++ that uses levels made out of tiles. The world class has an add(WorldObject* o) function that can both accept a tile or an entity such as an enemy. Both the Tile and the Entity class are derived from WorldObject. In every case, the object should be added to the entities list; but if it is a tile, it should also be added to the tiles list.

World.h

class World {
private:
    list<WorldObject*> content;
    list<Tile*> tiles;
public:
    void add(WorldObject*);
}

World.cpp

World.cpp

void World::add(WorldObject* o) {
    content.push_back(o);
    if(*o instanceof Tile) //What do I need to put here?
        tiles.push_back(o);
}

如何检查对象在C ++中是否具有特定类型？这与类型转换和虚函数以及类似的东西无关，因为我不想在此时调用对象的函数;如果它有某种类型，我只需要将它添加到一个单独的列表中。
在Java中，我可以执行 if（instance instanceof Class）。如何在C ++中执行此操作？

How do I check whether an object has a specific type in C++? It's nothing about typecasting and virtual functions and things like that because I don't want to invoke functions to the object at this time; I just need to add it to a separate list if it has a certain type. In Java, I can do if(instance instanceof Class). How can I do this in C++?

推荐答案

dynamic_cast 将检查看你是否可以将 o 转发给 Tile 。如果可以，它将返回有效的 Tile * ，否则它将返回null Tile * ：

A dynamic_cast will check to see if you can downcast o to Tile. If you can, it will return a valid Tile*, else it will return a null Tile*:

void World::add(WorldObject* o) {
    content.push_back(o);
    if (Tile* t = dynamic_cast<Tile*>(o)) {
        tiles.push_back(t);
    }
}

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