C, SDL: error: cannot convert 'SDL_Surface' to 'SDL_Surface (*)[15]

Question

so I'm working on a code for filling a screen with a table of surfaces; here's the code:

main.c

#ifdef __cplusplus
#include <cstdlib>
#else
#include <stdlib.h>
#endif

#include <SDL/SDL.h>
#include <SDL_image.h>
#include "maploader.h"

#define W 510
#define H 510
#define SIZE 34

void pause();

int main ( int argc, char** argv )
{
    SDL_Surface *screen = NULL;
    SDL_Surface *surfaces[15][15];



    SDL_Init(SDL_INIT_VIDEO);
    screen = SDL_SetVideoMode(W, H, 32, SDL_HWSURFACE | SDL_DOUBLEBUF);
    SDL_WM_SetCaption("demon game", NULL);
    SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 255, 255, 255));
    mapload(screen, surfaces[15][15], NULL);

    SDL_Flip(screen);
    pause();
    SDL_QUIT;
    return EXIT_SUCCESS;
}


void pause()
{
    int continuer = 1;
    SDL_Event event;

    while (continuer)
    {
        SDL_WaitEvent(&event);
        switch(event.type)
        {
            case SDL_QUIT:
            continuer = 0;
        }
    }
}

maploader.c

#ifdef __cplusplus
#include <cstdlib>
#else
#include <stdlib.h>
#endif

#include <SDL/SDL.h>
#include <SDL_image.h>
#define W 510
#define H 510
#define SIZE 34



SDL_Surface *surfaces[15][15];


void mapload(SDL_Surface *screen, SDL_Surface *surfaces[][15], int lvl)
{
    FILE *level = NULL;
    char elements[125];
    int i, j, k = 0;
    SDL_Rect elementposition = {0,0};


    level = fopen("level.txt", "r");
    if (level == NULL)
    {
        exit(0);
    }
    fgets(elements, 125, level);
    SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 255, 255, 255));
    for (i=0; i<15; i++)
    {
        for (j=0; j<15; j++)
        {
            if (elements[k] == "0")
            {
                surfaces[i][j] = IMG_Load("mur.jpg");
            }
            else if (elements[k] == "1")
            {
                surfaces[i][j] = IMG_Load("caisse.jpg");
            }
            else if (elements[k] == "2")
            {
                surfaces[i][j] = IMG_Load("objectif.png");
            }
            else
            {
                surfaces[i][j] = NULL;
            }
            k++;

        }

    }

    for (i=0; i<15; i++)
    {
        for (j=0; j<15; j++)
        {
            SDL_BlitSurface(surfaces[i][j], NULL, screen, &elementposition);
            elementposition.x += SIZE;
        }
        elementposition.y += SIZE;
    }




}

the only error I get from compiling is the following: "cannot convert 'SDL_Surface*' to 'SDL_Surface* ()[15]' for argument '2' to 'void mapload(SDL_Surface, SDL_Surface* (*)[15], int)'|"

apparently, the error is initialized from the second argument of the mapload function, but I don't have a clear idea about what exactly is wrong. any ideas, please?

The expression `surfaces[15][15]` get the *sixteenth* element of the *sixteenth* array from `surfaces`. I suggest you get [a good beginners book or two](http://stackoverflow.com/questions/562303/the-definitive-c-book-guide-and-list) and re-read the chapters on pointers and arrays. — Some programmer dude, Aug 28 '17 at 16:46
unrelated, but don't even try to write **source** files that are valid C **and** valid C++ ... nothing to gain here, but a lot to loose. `#ifdef __cplusplus` is for header files only, to describe your interface in a way usable from both languages. — , Aug 28 '17 at 16:47

Iharob Al Asimi · Answer 1 · 2017-08-28T16:51:46.450

This,

mapload(screen, surfaces[15][15], NULL);

should be

mapload(screen, surfaces, NULL);

But now you should ask yourself, if you didn't know that then probably,

The signature of void mapload(SDL_Surface *screen, SDL_Surface *surfaces[][15], int lvl) is altogether wrong.
You need to study what are arrays in c and their relation to pointers.

Note that surfaces[15][15] means the 16th element of the 16th array of pointers, none of which exists because you only allocated 15 of each. So you need to understand arrays in c, how they are allocated and how you can have a dynamic array.

Also, the fact that you tell a c compiler that a function is expecting an array is not very relevant inside such function, so the syntax SDL_Surface *surfaces[][15] seems strange to a c programmer.

And finally, since surfaces is a global variable you don't need to pass it as a parameter, but then you should ask yourself, should it be a global variable?

C, SDL: error: cannot convert 'SDL_Surface*' to 'SDL_Surface* (*)[15]

1 Answers1

C, SDL: error: cannot convert 'SDL_Surface' to 'SDL_Surface (*)[15]