Question

我在编译代码时遇到以下错误：

1>Mapa.obj : error LNK2019: unresolved external symbol "public: void __thiscall Mapa::Collision(float,float,float,float,int,int,int,int)" (?Collision@Mapa@@QAEXMMMMHHHH@Z) referenced in function "public: void __thiscall Mapa::mapa1(float,float,int,struct ALLEGRO_BITMAP *,struct ALLEGRO_BITMAP *,int)" (?mapa1@Mapa@@QAEXMMHPAUALLEGRO_BITMAP@@0H@Z)

Heder File

    class Mapa
{
public:
    Mapa(void);
    ~Mapa(void);
    void Mapa::mapa1(float xp, float yp,int dir,ALLEGRO_BITMAP *party, ALLEGRO_BITMAP *mapa1,int moveSpeed);
    void Mapa::Collision(float xp,float yp,float ex,float ey,int width,int height,int dir,int moveSpeed);
    //const float moveSpeed;
};

这是功能

    Mapa::Mapa(void)
{
}

Mapa::~Mapa(void)
{
}
enum Direction { DOWN, LEFT, RIGHT, UP };
int dir = DOWN; 
void Collision(float xp,float yp,float ex,float ey,int width,int height,int dir,int moveSpeed)
{
    if( xp + width < ex || xp> ex+ width || yp+ height <ey || yp > ey +height)
    {
    }
    else 
    {
            {
           if(dir==0)
         yp-=moveSpeed;
     else if(dir==1)
         xp+=moveSpeed;
     else if(dir==2)
         xp-=moveSpeed;
     else if(dir==3)
         yp+=moveSpeed;
    }
    }
}
void Mapa::mapa1(float xp, float yp,int dir,ALLEGRO_BITMAP *party,ALLEGRO_BITMAP *mapa1,int moveSpeed)
{

bool draw=true;
bool done=false;
bool active=false;
int sourceX,sourceY;
const float FPS = 60.0;
sourceX=0;
sourceY=0;
ALLEGRO_TIMER *timer = al_create_timer(1.0 / FPS);
ALLEGRO_KEYBOARD_STATE StatusKlawiatury1 ; // klawiatura
ALLEGRO_EVENT_QUEUE *event_queue = al_create_event_queue();
al_register_event_source(event_queue, al_get_keyboard_event_source());
al_register_event_source(event_queue, al_get_timer_event_source(timer));
    al_draw_bitmap(mapa1,0,0,0);
   al_start_timer(timer);
     while(!done)
    {
    ALLEGRO_EVENT events;
    al_wait_for_event(event_queue, &events);
    if(events.type == ALLEGRO_EVENT_KEY_UP)
        {
            switch(events.keyboard.keycode)
            {
            case ALLEGRO_KEY_ESCAPE:
                done = true;
            }
        }


    else if(events.type == ALLEGRO_EVENT_TIMER)
        {
            active=true;
            al_get_keyboard_state(&StatusKlawiatury1);
            if(al_key_down(&StatusKlawiatury1, ALLEGRO_KEY_DOWN))
            {
                yp += moveSpeed;
                dir= DOWN;
            }
            else if(al_key_down(&StatusKlawiatury1, ALLEGRO_KEY_UP))
            {             
                yp -= moveSpeed;
                dir = UP;
            }
            else if(al_key_down(&StatusKlawiatury1, ALLEGRO_KEY_RIGHT))
            {     
                xp += moveSpeed;
                dir= RIGHT;
            }
            else if(al_key_down(&StatusKlawiatury1, ALLEGRO_KEY_LEFT))
            {             
                xp -= moveSpeed;
                dir = LEFT;
            }
            else
                active = false;
            Collision(xp,yp,0,426,627,61,dir,moveSpeed);
            Collision(xp,yp,700,273,647,53,dir,moveSpeed);
            Collision(xp,yp,0,128,695,58,dir,moveSpeed);
            Collision(xp,yp,0,0,351,20,dir,moveSpeed);
            Collision(xp,yp,770,0,351,20,dir,moveSpeed);
            Collision(xp,yp,0,0,0,600,dir,moveSpeed);
            Collision(xp,yp,800,0,10,600,dir,moveSpeed);
            Collision(xp,yp,0,595,800,10,dir,moveSpeed);
            if(active)
                sourceX+=al_get_bitmap_width(party)/2;
            else
                sourceX=20;
            if(sourceX >=al_get_bitmap_width(party))
               sourceX=0;

                draw = true;
        }

        if(draw)
        {

            draw=false;
    al_convert_mask_to_alpha(party, al_map_rgb(255,0,255));
    al_draw_bitmap_region(party,sourceX,dir*al_get_bitmap_height(party)/4,20,20,xp,yp,NULL);
    al_flip_display();
    al_draw_bitmap(mapa1,0,0,0);

        }
    }
}

我花了几个小时搜索解决方案。当我在main中执行它们时，这两个函数都没有问题，但是当我将它们移到单独的类时，它开始显示错误。任何帮助都会被贬低。

Answer 1

函数定义中缺少类限定符Mapa::。

void Maoa::Collision(float xp,float yp,float ex,float ey,int width,int height,int dir,int moveSpeed)

Answer 2

错误中的“LNK”部分告诉您编译器成功，问题出在链接器中。 C ++只需要一个函数声明，用于调用所述函数进行编译的代码，但它还需要一个函数定义来链接。

在您的情况下，错误告诉您缺少Maoa::Collision的定义。实际上，代码中没有该成员的函数定义，只有名为Collision的全局函数的定义。

您需要从

更改功能定义

void Collision(float xp,float yp,float ex,float ey,int width,int height,int dir,int moveSpeed)

到

void Maoa::Collision(float xp,float yp,float ex,float ey,int width,int height,int dir,int moveSpeed)

错误：＆＃34;错误LNK2019：未解析的外部符号＆＃34;

2 个答案: