[Bugsy]

Agree, Trie or vault would make it easier.

nVault

Spoiler

PHP Code:


#include <amxmodx>
#include <nvault>

#define MAX_PLAYERS 32

new const SteamIDList[][] =
{
    "STEAM_6:0:40857791",
    "STEAM_6:0:1543600141",
    "STEAM_6:0:765433307"
};

new g_Vault , g_szAuthID[ MAX_PLAYERS + 1 ][ 34 ];

public plugin_init() 
{
    g_Vault = nvault_open( "SteamIDMenu" );
    
    LoadVault();
    
    register_clcmd( "say /menu" , "ShowMenu" );
}

public plugin_end()
{
    nvault_close( g_Vault );
}

public client_authorized( id )
{
    get_user_authid( id , g_szAuthID[ id ] , charsmax( g_szAuthID[] ) );    
}

public ShowMenu( id )
{
    if ( nvault_get( g_Vault , g_szAuthID[ id ] ) )
    {
        //Player in vault
    }
} 

LoadVault()
{
    nvault_prune( g_Vault , 0 , get_systime() );
    for ( new i = 0 ; i < sizeof( SteamIDList ) ; i++ )
    {
        nvault_set( g_Vault , SteamIDList[ i ] , "1" );
    }
} 


Trie

Spoiler

PHP Code:

#include <amxmodx>

#define MAX_PLAYERS 32

new const SteamIDList[][] =
{
    "STEAM_6:0:40857791",
    "STEAM_6:0:1543600141",
    "STEAM_6:0:765433307"
};

new Trie:g_Trie , g_szAuthID[ MAX_PLAYERS + 1 ][ 34 ];

public plugin_init() 
{    
    g_Trie = TrieCreate();
    
    for ( new i = 0 ; i < sizeof( SteamIDList ) ; i++ )
    {
        TrieSetCell( g_Trie , SteamIDList[ i ] , 1 );
    }
    
    register_clcmd( "say /menu" , "ShowMenu" );
}

public client_authorized( id )
{
    get_user_authid( id , g_szAuthID[ id ] , charsmax( g_szAuthID[] ) );    
}

public ShowMenu( id )
{
    if ( TrieKeyExists( g_Trie , g_szAuthID[ id ] ) )
    {
        //Player in trie
    }
}