SDL vulkan explanation...

sdl-vulkan-explanation.cpp

/*
Ok, I answered too quickly, and Twitter is terrible for this, so have a gist.

You call this function twice: the first time with a NULL and it just sets
extension_count to the number of strings it plans to give you, so you can
allocate space for them and call the function again.
*/

// (you should check return values for errors in all this, but whatever.)
unsigned int count = 0;
const char **names = NULL;
SDL_Vulkan_GetInstanceExtensions(window, &count, NULL);

// now count is (probably) 2. Now you can make space:
names = new const char *[count];

// now call again with that not-NULL array you just allocated.
SDL_Vulkan_GetInstanceExtensions(window, &count, names);

// Now names should have (count) strings in it:

for (unsigned int i = 0; i < count; i++) {
    printf("Extension %d: %s\n", i, names[i]);
}

// use it for VkInstanceCreateInfo and when you're done, free it:

delete[] names;

// Ship your successful C++ game and retire a millionaire. THE END.  --ryan.

Hi, it still returns as 0 here 😕