Random bits of SDL code

//String input

class StringInput
{
    private:
    std::string str;
    SDL_Surface *Text;
    public:
    StringInput();
    ~StringInput();
    void HandleInput();
    void ShowCentered();
};


StringInput::StringInput()
{
    str = "";
    Text = NULL;
    SDL_EnableUNICODE( SDL_ENABLE );
}

StringInput::~StringInput()
{
    SDL_FreeSurface( Text );
    SDL_EnableUNICODE( SDL_DISABLE );
}

void StringInput::HandleInput()
{
    if( event.type == SDL_KEYDOWN )
    {
        std::string temp = str;
        if( str.length() <= 6 )
        {
            if( event.key.keysym.unicode == (Uint16)' ' )
            {
                str += (char)event.key.keysym.unicode;
            }
            else if( ( event.key.keysym.unicode >= (Uint16)'0' ) && ( event.key.keysym.unicode <= (Uint16)'9' ) )
            {
                str += (char)event.key.keysym.unicode;
            }
            else if( ( event.key.keysym.unicode >= (Uint16)'A' ) && ( event.key.keysym.unicode <= (Uint16)'Z' ) )
            {
                str += (char)event.key.keysym.unicode;
            }
            else if( ( event.key.keysym.unicode >= (Uint16)'a' ) && ( event.key.keysym.unicode <= (Uint16)'z' ) )
            {
                str += (char)event.key.keysym.unicode;
            }
        }
        if( ( event.key.keysym.sym == SDLK_BACKSPACE ) && ( str.length() != 0 ) )
        {
            str.erase( str.length() - 1 );
        }
        if( str != temp )
        {
            SDL_FreeSurface( Text );
            text = TTF_RenderText_Solid( font, str.c_str(), TextColour );
        }
    }
}

void StringInput::ShowCentered()
{
    if( Text != NULL )
    {
        ApplySurface( ( ScreenWidth - BlackRectangle -> w) / 2, (ScreenHeight - BlackRectangle->h)/2, BlackRectangle, Screen);
        ApplySurface( ( ScreenWidth - Text->w ) / 2, ( ScreenHeight - Text->h ) / 2, Text, screen );
    }
}