[Konstantinos]

pawn Код:

#if !defined isnull
    #define isnull(%1) \
                ((!(%1[0])) || (((%1[0]) == '\1') && (!(%1[1]))))
#endif

pawn Код:

if(isnull(params)) return SendClientMessage(playerid, COLOR_WHITE, "USAGE: /bizname [name]");
// rest..