Didn't really understand what you're doing but maybe this is what you need (only an example).
Code:
// Max players server can hold
#define MAX_PLAYERS 32
// Max IDs that can be stored in an array + 1
// Max characters of SteamID
new g_SteamID[MAX_PLAYERS + 1][32];
// Client is authorized, store his ID in g_SteamID
public client_authorized(Client)
{
// Local array which will hold the SteamID of Client
new SteamID[32];
// Get user SteamID and store it in SteamID array
get_user_authid(Client, SteamID, 31);
// Store data from SteamID array to g_SteamID global array
formatex(g_SteamID[Client], 31, SteamID);
}
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