blocks|key|86313|text|您可以按如下方式存储它们|type|unstyled|depth|inlineStyleRanges|entityRanges|data|86314|std::vector<Component+*>+components;
Component+*+c+=+new+Health;
components.push_back(+c+);|code-block|syntax|javascript|86315|调用components[0]+->+method();将调用Health的method()|offset|length|style|CODE|86316|这就是在C%2B%2B中实现多态性的方式。|86317|还要确保组件的method()为virtual|86318|entityMap^0|0|0|2|Q|V|6|12|8|0|0|7|8|G|7|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]|$I|X|J|Y|K|L]|$I|Z|J|10|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|12|8|@$I|13|J|14|K|L]|$I|15|J|16|K|L]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$]]

you store them as follow

<pre><code>std::vector&lt;Component *&gt; components;
Component * c = new Health;
components.push_back( c );
</code></pre>

calling <code>components[0] -&gt; method();</code> will invoke <code>method()</code> of <code>Health</code>

This is how polymorphism is done in C++.

Also make sure <code>method()</code> of Component is <code>virtual</code>

blocks|key|1229651|text|您可以存储指向基类对象的智能指针的vector，然后可以向其中添加派生类的objects。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1229652|例如：|1229653|+std::vector<std::unique_ptr<Component>+>+base;
+Component.push_back(+std_unique_ptr<Component>(new+SceneGraphNode())+);+
++++++++++++//%5E%5Euse+correct+constructor,+this+example+just+show+the+methodology
+Component.push_back(+std_unique_ptr<Component>(new+Renderable())+);|code-block|syntax|javascript|1229654|entityMap^0|H|6|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

You can store a <code>vector</code> of smart pointers that points to base class objects, then you can add derived class obejects into it.

For example:

<pre><code> std::vector&lt;std::unique_ptr&lt;Component&gt; &gt; base;
 Component.push_back( std_unique_ptr&lt;Component&gt;(new SceneGraphNode()) ); 
 //^^use correct constructor, this example just show the methodology
 Component.push_back( std_unique_ptr&lt;Component&gt;(new Renderable()) );
</code></pre>

blocks|key|1226005|text|允许您拥有指向子类对象的基类指针，即Component+*+sgn+=+new+SceneGraphNode|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1226006|因此，分配一个Component*数组(如果需要改变大小，则分配一个向量)，并使每个入口点指向一个派生对象。|1226007|Component+*+components[100];
components[0]+=+new+SceneGraphNode;
components[1]+=+new+Renderable;
//+so+on+and+so+on|code-block|syntax|javascript|1226008|此外，对于要在子类中定义的任何成员函数，必须在组件中具有虚拟函数|1226009|class+Component+{
++++public:
++++++++virtual+void+method()+=+0;
++++++++virtual+int+method2(int+arg)+=+0;
};

class+SceneGraphNode+:+public+Component+{
++++public:
++++++++virtual+void+method(){
++++++++++++//body
++++++++}
++++++++virtual+int+method2(int+arg){
++++++++++++return+arg*2;
++++++++}
};|1226010|virtual关键字使得它可以在运行时查看指向对象的实际类型并调用其方法，而不是调用指针类型方法。这就是java做事情的正常方式。=+0使函数成为“纯虚拟的”，这意味着子类必须定义该方法。使用上面定义的数组...|BOLD|1226011|components[0]->method();
compenents[2]->method2(1);|1226012|如果您更喜欢向量而不是数组，可以将数组版本替换为：|1226013|#include+<vector>;
//...
std::vector<Component*+>+components;
components.push_back(new+SceneGraphNode);
components.push_back(new+Renderable);|1226014|entityMap^0|I|10|0|7|A|0|0|0|0|0|7|1T|3|2E|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|17|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|18|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|19|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|S]]|D|@]|E|$]]|$1|T|3|U|5|J|7|1H|8|@]|D|@]|E|$K|L]]|$1|V|3|W|5|6|7|1I|8|@]|D|@]|E|$]]|$1|X|3|Y|5|J|7|1J|8|@]|D|@]|E|$K|L]]|$1|Z|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]]|10|$]]

You are allowed to have a Base class pointer to a child class object, ie
<code>Component * sgn = new SceneGraphNode</code>

So allocate an array of <code>Component*</code>s (or a vector if it needs to vary in size) and make each entry point to a derived object.

<pre><code>Component * components[100];
components[0] = new SceneGraphNode;
components[1] = new Renderable;
// so on and so on
</code></pre>

In addition to this you must have virtual functions in Component for any member function you intend to define in the child classes

<pre><code>class Component {
 public:
 virtual void method() = 0;
 virtual int method2(int arg) = 0;
};

class SceneGraphNode : public Component {
 public:
 virtual void method(){
 //body
 }
 virtual int method2(int arg){
 return arg*2;
 }
};
</code></pre>

The <code>virtual</code> keyword makes it so that at runtime it looks at the actual type of the pointed to object and calls its method, rather than calling the pointer types method. This is how java does things normally. The <code>= 0</code> makes the function "pure virtual" meaning that a child class must define that method. Using our array defined above...

<pre><code>components[0]-&gt;method();
compenents[2]-&gt;method2(1);
</code></pre>

If you would prefer a vector to an array, you can replace the array version with:

<pre><code>#include &lt;vector&gt;;
//...
std::vector&lt;Component* &gt; components;
components.push_back(new SceneGraphNode);
components.push_back(new Renderable);
</code></pre>

In C++ I have a series of structures defined...

<pre><code>struct Component {};
struct SceneGraphNode : Component {};
struct Renderable : Component {};
struct Health : Component {};
</code></pre>

These could easily be classes, I've been told that there is very little difference in C++.

In Java it is possible to declare an array of type <code>Component</code> and put any class that extends from (inherits) <code>Component</code> into it. Java considers them all components and since everything uses smart pointers, Java's "array" is really just a list of smart-pointers which are all the same size. 

However I understand that Java handles arrays significantly different from C++. When I checked the size of each of these structs I got the following. 

<pre><code>Component // 4
SceneGraphNode : Component // 8
Renderable : Component // 8
Health : Component // 20
</code></pre>

Which isn't suprising. Now when I create an array of Components, the size of the blocks are obviously going to be 4 (bytes) which won't hold any of the other structures.

So my question is, how can I store a loose list of <code>Components</code> (IE a list that can store any class / struct that inherits from Component)? In Java this is mind-numbingly simple to do. Surely there must be an easy way in C++ to do it.

C++ store any child struct/class in array?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在C++中，我定义了一系列结构...struct Component {};struct SceneGraphNode : Component {};struct Renderable : Component {};struct Health : Component {};这些很容易成为类，我被告知在C++中几乎没有什...

问C++是否在数组中存储任何子结构/类？
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问C++是否在数组中存储任何子结构/类？EN