c++ - C++编译顺序

Question

[演员.h]

#include "../PathEngine/Actor.h"
namespace FightEngine
{
    class Actor
        :public PathEngine::Actor
    {
    private:
        .....
    public:
        Actor();
        ~Actor();
        void SetPosition(int x, int y);
    };
}

[演员.cpp]

#include "Actor.h"
namespace FightEngine
{
    Actor::Actor()
        :PathEngine::Actor()
    {
        do something
    }
    Actor::~Actor()
    {

    }
    void Actor::SetPosition(int x, int y)
    {
        do something
    }
}

[主.cpp]

FightEngine::Actor* actor = new FightEngine::Actor();
actor->SetPosition(400,200);

它给了我一些

>

错误 LNK2019：未解析的外部符号....

我猜 Actor::SetPosition(x,y)、Actor::Actor() 已声明但未定义。但我实际上在 Actor.cpp 中定义了它。问题是编译器不编译 Actor.cpp，我不知道为什么。