[(SF)Noobanatior]

GetTickcount when the player connects and save it
GetTickcount when the player disconnects and save it
(disconect time) - (Connect time) = time online
then just convert ticks into seconds

pawn Код:

stock PlayerConnectTime(playerid) {
    PlayerTime[playerid][tConnect] = GetTickCount();
}

stock PlayerDisconnectTime(playerid) {
  PlayerTime[playerid][tDisconnect] = GetTickCount();
  PlayerTime[playerid][tOnline] = floatdiv((PlayerTime[playerid][tDisconnect] - PlayerTime[playerid][tConnect]),6000);
  PlayerTime[playerid][tTotal] += PlayerTime[playerid][tOnline];
}

this is how i do it