Errors in Xcode using SDL

Question

I am using Lazy Foo's Production tutorials for making an SDL game in C in Xcode 6.1 - http://lazyfoo.net/tutorials/SDL/index.php#Hello%20SDL. I'm using Xcode 7 but I don't think they are very different.

In the second tutorial (http://lazyfoo.net/tutorials/SDL/02_getting_an_image_on_the_screen/index.php). I cannot seem to compile properly without an error regarding one of the functions.

The function prototype:

//Frees media and shuts down SDL
void close();

Then the function declaration:

void close()
{
    //Deallocate surface
    SDL_FreeSurface( gHelloWorld );
    gHelloWorld = NULL;

    //Destroy window
    SDL_DestroyWindow( gWindow );
    gWindow = NULL;

    //Quit SDL subsystems
    SDL_Quit();
}

And then the function call at the end:

close();

I am getting these errors and am not quite sure how to fix them. Other solutions online are for problems that are not quite the same as mine.

SDL_Tutorial/SDL_Tutorial/using_image.c:28:6: Conflicting types for 'close'

SDL_Tutorial/SDL_Tutorial/using_image.c:28:6: Conflicting types for 'close'

SDL_Tutorial/SDL_Tutorial/using_image.c:127:5: Implicit declaration of function 'close' is invalid in C99

SDL_Tutorial/SDL_Tutorial/using_image.c:127:11: Too few arguments to function call, expected 1, have 0

clang: error: linker command failed with exit code 1 (use -v to see invocation)

Any help would be much appreciated, as I am struggling to make progress with learning SDL game programming at the moment.

Thank you.

Answer 1

The lazyfoo tutorials don't have the best coding practices. I can see two problems:

• close is too generic of a name for a function. It's most likely conflicting with an existing function with the same signature. You should rename the function.
• In C, void foo() is not the right way to declare "a function that takes no arguments and returns nothing". It's void foo(void). You should either fix the declaration, or compile your code as C++, as lazyfoo assumes (note that if you download their code their files are inside .cpp files). In C++ void foo() is a correct declaration.