[Twisted_Insane]

Or, you're checking it with a boolean:

pawn Код:

bool:loggedIn[MAX_PLAYERS];

Under "OnPlayerLogin" add this:

pawn Код:

loggedIn[playerid] == true;

Then, you could - as Dwane already said - check whether the player's logged in or not:

pawn Код:

public OnPlayerRequestClass(playerid, classid)
{
  if(loggedIn[playerid] == false)
  {
    SendClientMessage(playerid, -1, "You'll have to login before changing / choosing classes!");
    return 0;
  }
   //rest