[Konstantinos]

It depends on what you want to do.

Use either:

pawn Код:

forward OnPlayerLogin(playerid, password[]);
public OnPlayerLogin(playerid, password[])

or:

pawn Код:

forward OnPlayerLogin(playerid, uid);
public OnPlayerLogin(playerid, uid)

However, in some cases you enter as second parameter string and somewhere else an integer. What do you want? It must be one of them.

In this line "if(strcmp(keystring, uid, true) == 0)" you check if an integer is equal to a string and that's why it gives you an error.

Was uid supposed to be the "password" of the player?