Thread: linker 2019 issues

Hi,

I have been playing around with SDL recently and also trying to learn more about classes and pointers too. I have a problem with code I have implented from this site http://www.aaroncox.net/tutorials/2d...dlclasses.html

Player.obj : error LNK2019: unresolved external symbol "public: struct SDL_Surface * __thiscall SDL_Graphics::Load_Image(char *,int,int,int)" (?Load_Image@SDL_Graphics@@QAEPAUSDL_Surface@@PADH HH@Z) referenced in function "public: __thiscall Player::Player(class SDL_Graphics *,int,int,int,int,int,int,int,char *,float,float,float)" (??0Player@@QAE@PAVSDL_Graphics@@HHHHHHHPADMMM@Z)

is the error.

here is some of the code....

Code:

#ifndef PLAYER_H
#define PLAYER_H

#include "sdl.h"
#include "sdlinit.h"


class Player
{
public:
	  Player(SDL_Graphics* screen,
             int imageX, int imageY,
             int width, int height,
             int transparentR, int transparentG, int transparentB,
             char* FileName,
             float x, float y,
             float maxSpeed);

   ~Player();
	void MoveLeft();
	void MoveRight();
	void MoveUp();
	void MoveDown(); // these 4 adjust the characters position based on the speed in pixels
	void StopMoving();
	void Update(float deltatime); // this adjusts the speed to make it work to pixels per second.

private:
	SDL_Graphics* screen;
	SDL_Surface* playerimage;
	float maxspeed ; // speed in pixels per second.
	float currentspeedx;
	float currentspeedy;
	float x;
	float y; //  position on screen
	float Width;
	float Height;
	float imagex;
	float imagey;

};
#endif

player.cpp
#include "Player.h"


Player::Player(SDL_Graphics* screen,int imageX, int imageY,int width, int height,
				int transparentR, int transparentG, int transparentB,
				char* FileName,float x, float y,float maxSpeed)
								: screen(screen),
                                  imagex(imageX), imagey(imageY),
                                  Width(width), Height(height),
                                  x(x), y(y),
                                  maxspeed(maxSpeed),
                                  currentspeedx(0.0f)
{
	playerimage = screen->Load_Image(FileName, transparentR, transparentG, transparentB);
}
Player::~Player()
   {
	   screen->CloseImage(playerimage);
   }

void Player::MoveLeft()
	{
	}
void Player::MoveRight()
	{
	}

void Player::MoveUp()
{
}
void Player::MoveDown() // these 4 adjust the characters position based on the speed in pixels
{
}

void Player::StopMoving()
{
}


void Player::Update(float deltatime) // this adjusts the speed to make it work to pixels per second.
	{

	}
sdlinit.h
#ifndef SDLINIT_H
#define SDLINIT_H

#include "sdl.h"
#include "SDL_TTF.h"
#include "SDL_Image.h"

class SDL_Graphics
{
public:
	SDL_Graphics(int width, int height, char* windowtitle, int Red , int Green , int Blue );
	~SDL_Graphics();
	
	SDL_Surface* Load_Image(char* filename, int Red, int Green, int Blue);
	void CloseImage(SDL_Surface* image);
	void BackgroundColour(int Red,int Green,int Blue);
	void Drawtext(int xpos, int ypos, char* message, int Red, int Green, int Blue, int fontsize);
	void DrawSprite(SDL_Surface* imageSurface, int srcX, int srcY, int dstX, int dstY, int width, int height);
	void Flip();
	void BeginScene();
	void EndScene();

private:
	SDL_Surface* screen;
	int BackRed;
	int BackGreen;
	int BackBlue;
};
#endif
sdlinit.cpp
#include "sdlinit.h"

SDL_Graphics::SDL_Graphics(int width, int height, char* windowtitle, int Red, int Green, int Blue)
{
	SDL_Init( SDL_INIT_VIDEO );
	TTF_Init();
	screen = SDL_SetVideoMode( width, height,0,SDL_HWSURFACE | SDL_DOUBLEBUF);
	SDL_WM_SetCaption( windowtitle, 0 );
	BeginScene();
	BackRed = Red; BackGreen = Green; BackBlue = Blue;
}
void SDL_Graphics::BeginScene()
{
		SDL_FillRect(screen,
		NULL,
		SDL_MapRGB(screen->format,BackRed,BackGreen,BackBlue));
}
void SDL_Graphics::EndScene()
{
	SDL_Flip(screen);
}
SDL_Surface* Load_Image(char* filename, int red, int green, int blue)
{
	SDL_Surface* tempimage = NULL;
	tempimage = IMG_Load(filename);
	if (tempimage == NULL)
		return NULL;
	SDL_SetColorKey(tempimage,SDL_SRCCOLORKEY,SDL_MapRGB(tempimage->format, red, green, blue)); 
	return tempimage;
}

void CloseImage(SDL_Surface* image)
{
	SDL_FreeSurface(image);
}

void SDL_Graphics::BackgroundColour(int Red = 0 , int Green = 0, int Blue = 0)
{
	BackRed = Red; BackGreen = Green; BackBlue = Blue;
}
SDL_Graphics::~SDL_Graphics()
{
	SDL_Quit();
	TTF_Quit();
}
void SDL_Graphics::Drawtext(int xpos, int ypos, char* message, int Red, int Green, int Blue, int fontsize)
{
	TTF_Font* font = TTF_OpenFont("c:\\windows\\fonts\\arial.ttf", fontsize);
	SDL_Color Colour = {Red,Green,Blue};
	if (font == NULL)
		return;

	SDL_Surface* textsurface;
	textsurface = TTF_RenderText_Blended(font, message, Colour);
	SDL_Rect textlocation = {xpos,ypos,0,0};
	SDL_BlitSurface(textsurface,NULL,screen,&textlocation);
	SDL_FreeSurface(textsurface);
	TTF_CloseFont(font);
}

void SDL_Graphics::Flip()
{
	SDL_Flip(screen);
}

void SDL_Graphics::DrawSprite(SDL_Surface* imageSurface, int srcX, int srcY, int dstX, int dstY, int width, int height)
{
   SDL_Rect srcRect;
   srcRect.x = srcX;
   srcRect.y = srcY;
   srcRect.w = width;
   srcRect.h = height;

   SDL_Rect dstRect;
   dstRect.x = dstX;
   dstRect.y = dstY;
   dstRect.w = width;
   dstRect.h = height;

   SDL_BlitSurface(imageSurface, &srcRect, screen, &dstRect);
}

the problems lies in the constructor for the Player class where it calls the SDL_Graphics classes function LoadImage().

It also has a problem with CloseImage.

I think it is something I have done wrong with my classes.

I've been googling and am unable to come up with a solution to my problem so far. which makes me think its something to do with my classes. if I comment out the calls to the Loadimage and close image in my player constructor and destructor it links ok.

any help or advice would be greatly appreciated.

Is sdlinit.cpp in your project?
You need to compile all your .cpp files.

Code:

SDL_Surface* Load_Image(char* filename, int red, int green, int blue);
void CloseImage(SDL_Surface* image);

Note how they are defined in the global namespace and not as part of the class (missing SDL_Graphics::).

i knew it would be something simple that i had done wrong!

thanks!