I've recently dived into some SDL tutorials, but am having difficulty compiling this one in particular using DevC++ with the SDL library: http://lazyfoo.net/SDL_tutorials/lesson05/index.php

I am getting this particular error: `filename' undeclared (first use this function) and it points to the filename.c_str() ); area of the code, as well as a few others listed in the compile log. I'd like to also investigate the "apply_surface" not being recognized as well. I have included the following headers:

#include <cmath>

#include <string>

#include <vector>

#include <iostream>

#include "SDL/SDL.h"

#include "quickcg.h"

#include "SDL/SDL_mixer.h"

#include "SDL/SDL_image.h"

#include "SDL/SDL_ttf.h"

using namespace QuickCG;

Linker options include suggestions based on other threads I've found with the same issue, it appears I'm not alone but I haven't quite found the solution that applies to my code yet:

-lmingw32

-mwindows

-lSDLmain

-lSDL

-lSDL_mixer

-lSDL_image

-lSDL_ttf

-lstdc++

CODE SNIPPET:

	
		
			
				 
			
				<pre>
int main(int /*argc*/, char */*argv*/[])
{
    {
    SDL_Surface* title = NULL;
    SDL_Surface* hud = NULL;
    SDL_Surface* screen = NULL;
    SDL_Surface* loadedImage = NULL;
    SDL_Surface* optimizedImage = NULL;

    loadedImage = IMG_Load( filename.c_str() );

    if (loadedImage != NULL)
    {
        optimizedImage = SDL_DisplayFormat( loadedImage );
        SDL_FreeSurface( loadedImage );
        if( optimizedImage != NULL)</pre>
			
		
	

etc etc

COMPILE LOG:

Compiler: Default compiler

Building Makefile: "D:\Coding\Raycaster\Makefile.win"

Executing make...

make.exe -f "D:\Coding\Raycaster\Makefile.win" all

g++.exe -c raycaster.cpp -o raycaster.o -I"D:/Coding/Dev-Cpp/lib/gcc/mingw32/3.4.2

/include" -I"D:/Coding/Dev-Cpp/include/c++/3.4.2/backward" -I"D:/Coding/Dev-Cpp

/include/c++/3.4.2/mingw32" -I"D:/Coding/Dev-Cpp/include/c++/3.4.2" -I"D:/Coding

/Dev-Cpp/include" -fexpensive-optimizations -O3 -mwindows



raycaster.cpp: In function `int SDL_main(int, char**)':

raycaster.cpp:117: error: `filename' undeclared (first use this function)

raycaster.cpp:117: error: (Each undeclared identifier is reported only once for

each function it appears in.)



raycaster.cpp:130: error: invalid conversion from `SDL_Surface*' to `int'

raycaster.cpp:133: error: `apply_surface' undeclared (first use this function)

raycaster.cpp:134: error: `hud' undeclared (first use this function)



make.exe: *** [raycaster.o] Error 1



Execution terminated

Any suggestions or advice would be greatly appreciated. I'm yet another newbie to the whole C++ scene, but this is more of a learning experiment than anything else.

Well, you seem to have simply copy/pasted a few lines of code out of the working tutorial code.

Your main issue right now seems to be to read errors properly.

1)

The filename. You pasted a few lines from a function, which had parameter as a function argument. Obviously that argument is not here, so you have to declare filename yourself above the location where you access it. The compiler simply doesn't know what "filename" is (Hint: In the tutorial code it's a std::string)

2)

apply_surface is the same. It's a function defined in the tutorial code. You only copied lines calling that function. The compiler obviously does not know the function.

Simple solution: Copy also the apply_surface function and paste it above the main function.

Thankyou for your reply!

Have gotten the code to compile without error, however when I run the program, the exe window pops up for about 1 split second and then disappears instantly. Despite it being advised against, I've tried using system pause to keep it from disappearing but to no avail. Is there something wrong with how I'm setting the project up perhaps?

I've noticed this happens for a few of the tutorials on the site, but not all. The play sound/display images tutorials have worked fine.

Old (and buggy) IDE, (very) old GCC, old library.

Upgrade those and tackle LazyFoo's SDL2 tutorials.

Old (and buggy) IDE, (very) old GCC, old library.

Upgrade those and tackle LazyFoo's SDL2 tutorials.

Thankyou; was considering trying a different IDE altogether (Visual Studio or Code::blocks), and I'll get onto SDL2 straight away. Fingers crossed.