enum pInfo
{
    Slots,
    // Other stuff here, not important
}

new PlayerInfo[MAX_PLAYERS][pInfo];

public OnPlayerConnect(playerid)
{
    print("OnPlayerConnect was called.");
    PlayerInfo[playerid][Slots] = 5;
    return 1;
}

[19:10:51] 
[19:10:51] Filterscripts
[19:10:51] ---------------
[19:10:51]   Loading filterscript 'testfs.amx'...
[19:10:51] OnFilter
[19:10:51]   Loaded 1 filterscripts.

[19:10:51] OnGameo
[19:10:51] Number of vehicle models: 0
[19:11:12] Incoming connection: 127.0.0.1:52821
[19:11:12] [join] Torran has joined the server (0:127.0.0.1)
[19:11:21] [part] Torran has left the server (0:1)

public OnPlayerConnect(playerid)
{
    return 1;
}