枚举类型错误C2677

Question

my problem is, i got this enum type declared in my Button.h file:

enum ButtonEnum
    {
        BUTTON_SPRITE_MOUSE_UP_RED = 0,
        BUTTON_SPRITE_MOUSE_UP_VIOLET = 1,
        BUTTON_SPRITE_MOUSE_UP_DBLUE = 2,
        BUTTON_SPRITE_MOUSE_UP_GREY = 3,
        BUTTON_SPRITE_MOUSE_UP_DGREEN = 4,
        BUTTON_SPRITE_MOUSE_UP_LBLUE = 5,
        BUTTON_SPRITE_MOUSE_UP_LGREEN = 6,
        BUTTON_SPRITE_MOUSE_UP_YELLOW = 7,
        BUTTON_SPRITE_MOUSE_UP_EMPTY = 8,
        BUTTON_SPRITE_TOTAL = 9
    };

Later, i declare this:

ButtonEnum mCurrentSprite;

and use it in other function in Button.cpp:

void Button::render()
{
    SDLFunctions::render(mPosition.x,mPosition.y,SDLFunctions::gSpriteClips[mCurrentSprite] );
}

SDLFunctions::render looks like that:

void SDLFunctions::render( int x, int y, SDL_Rect* clip )
{
    //Set rendering space and render to screen
SDL_Rect renderQuad = { x, y, mWidth, mHeight };

//Set clip rendering dimensions
if( clip != NULL )
{
    renderQuad.w = clip->w;
    renderQuad.h = clip->h;
}

//Render to screen
SDL_RenderCopy( gRenderer, mTexture, clip, &renderQuad );
}

and SDLFunctions::gSpriteClips is this:

SDL_Rect gSpriteClips[ 9 ];

which in another function is filled with some values. To the point. Building program results with this: error C2677: binary '[' : no global operator found which takes type 'Button::ButtonEnum' (or there is no acceptable conversion)

And my question is: what the hell? What is wrong with this? mCurrentSprite got declared starting value in builder, and everytime Button::render is called, it got some value, its not NULL. Can someone solve it? Thanks.

Answer 1

Your compiler is trying to tell you (in a very unclear way) that you are indexing into an array using an enum. That's not really allowed--enums have integral values, but they aren't integer types. So you need to cast it:

SDLFunctions::render(mPosition.x, mPosition.y,
    SDLFunctions::gSpriteClips[static_cast<size_t>(mCurrentSprite)]);