It doesn't matter how many slots you have. The player id can range from 1 to 32 and you should always use [33] when using player variables. Loop all players like this:
PHP Code:
new iPlayers[32], iPnum
get_players(iPlayers, iPnum)
for(new iPlayer, i; i < iPnum; i++)
{
iPlayer = iPlayers[i]
// iPlayer is the player id
}
You can also add filtering flags if you want only alive players, only CTs, etc.