[Joe_]

pawn Код:

Name(playerid)
{
    new pname[MAX_PLAYER_NAME];
    GetPlayerName(playerid, pname, MAX_PLAYER_NAME);
    return pname;
}

Now you can use it like this

pawn Код:

if(strcmp(Name(playerid), "Joe_", true))
{
    //stuff
}

Hope this helps.

OR you can use an enum.

pawn Код:

enum stuff
{
    name[MAX_PLAYER_NAME]
};

new st00f[MAX_PLAYERS][stuff];

public OnPlayerConnect(playerid)
{
    new n[MAX_PLAYER_NAME]; GetPlayerName(playerid, n, MAX_PLAYER_NAME);
    st00f[playerid][name] = n;

    return 1;
}

I preferably use the enum methord, but I change MAX_PLAYERS to my own value, otherwise your script will have to loop through 500.