Question

我收到此错误

对第22行的`InputHandler :: InputHandler（）'的未定义引用

我正在研究SDL中的InputHandler类

InputHandler.h

/*
 * InputHandler.h
 *
 *  Created on: 16 apr. 2014
 *      Author: JAN
 */

#ifndef INPUTHANDLER_H_
#define INPUTHANDLER_H_

#include "SDL2/SDL.h"
#include "Vector2D.h"

class InputHandler
{
public:

    static InputHandler* Instance()
    {
        if(s_pInstance == 0)
        {
            s_pInstance = new InputHandler();
        }

        return s_pInstance;
    }



    void reset();

    // update and clean the input handler
    void update();
    void clean();

    // keyboard events
    bool isKeyDown(SDL_Scancode key) const;

    // joystick events
    int getAxisX(int joy, int stick) const;
    int getAxisY(int joy, int stick) const;
    bool getButtonState(int joy, int buttonNumber) const;

    // mouse events
    bool getMouseButtonState(int buttonNumber) const;
    Vector2D* getMousePosition() const;

private:

    InputHandler();
    ~InputHandler();

    InputHandler(const InputHandler&);
    InputHandler& operator=(const InputHandler&);

    // private functions to handle different event types

    // handle keyboard events
    void onKeyDown();
    void onKeyUp();

    // handle mouse events
    void onMouseMove(SDL_Event& event);
    void onMouseButtonDown(SDL_Event& event);
    void onMouseButtonUp(SDL_Event& event);

    // handle joysticks events
    void onJoystickAxisMove(SDL_Event& event);
    void onJoystickButtonDown(SDL_Event& event);
    void onJoystickButtonUp(SDL_Event& event);

    // member variables

    // keyboard specific
    const Uint8* m_keystates;

    // singleton
    static InputHandler* s_pInstance;
};
typedef InputHandler TheInputHandler;
#endif

InputHandler.cpp

/*
 * InputHandler.cpp
 *
 *  Created on: 16 apr. 2014
 *      Author: JAN
 */

#include "InputHandler.h"
#include "Game.h"

InputHandler* InputHandler::s_pInstance = 0;


bool InputHandler::isKeyDown(SDL_Scancode key) const
{
    if(m_keystates != 0)
    {
        if(m_keystates[key] == 1)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    return false;
}


void InputHandler::update()
{
    SDL_Event event;
    while(SDL_PollEvent(&event))
    {
        switch (event.type)
        {

            case SDL_KEYDOWN:
                onKeyDown();
                break;

            case SDL_KEYUP:
                onKeyUp();
                break;

            default:
                break;
        }
    }
}

void InputHandler::onKeyDown()
{
    m_keystates = SDL_GetKeyboardState(0);
}

void InputHandler::onKeyUp()
{
    m_keystates = SDL_GetKeyboardState(0);
}

我是使用c ++编程并使用SDL的新手。所以这可能是一个愚蠢的错误，但如果有人能解释我会很棒！有点坚持这个现在不知道我做错了什么

Answer 1

您还没有在任何地方定义默认构造函数将其添加到cpp文件中。

你似乎也缺少其他一些成员。

Answer 2

在类InputHandler中，构造函数必须是这样的：InputHandler（）{}

未命名的引用`InputHandler :: InputHandler（）'

2 个答案: