[Bugsy]

Originally Posted by joaquimandrade Bitsums can't be used to replace is_user_alive like you have it, because 1<<32 is out of the bits that a cell can hold.

This is correct, since a 4 byte cell has 32 bits:
1 = 0000 0000 0000 0000 0000 0000 0000 0001

Doing a left shift of 32 will push the bit out of the bitfield:
1 << 32 = 1 0000 0000 0000 0000 0000 0000 0000 0000

You can make it work to hold player indexes (1-32) by subtracting 1 from the left-shift value so you will always shift 1 less (0-31 instead of 1-32). I used bit-fields in my Admin Hierarchy plugin instead of using arrays of 33 cells. The bit-field method is also nice because you can quickly check if any admins or bots are on the server with a simple !g_Bot or !g_Admin.

I cannot get the profiler to work so I'm not sure which way is ultimately better. The bit-field is better to conserve memory as you are using 1 cell (4 bytes) vs. a 33 cell array (132 bytes) as a storage mechanism for player indexes. On the other hand, the array method may be less CPU expensive but it will obviously utilize more memory.

PHP Code:

#define AddFlag(%1,%2)       ( %1 |= ( 1 << (%2-1) ) )
#define RemoveFlag(%1,%2)    ( %1 &= ~( 1 << (%2-1) ) )
#define CheckFlag(%1,%2)     ( %1 & ( 1 << (%2-1) ) )

new g_Admin;
new g_Bot;

public client_putinserver(id)
{
    if ( is_user_admin( id ) )
    {
        //An admin connected, add a bit to the g_Admin bitfield for this players id
        AddFlag( g_Admin , id );
    }

    if ( is_user_bot( id ) )
        AddFlag( g_Bot , id );
}

public client_disconnect(id)
{
    if ( CheckFlag( g_Bot , id ) )
    {
        //bot disconnected
        RemoveFlag( g_Bot , id );
    }
}

public YourFunction(id)
{
    if ( !CheckFlag( g_Admin , id ) )
    {
        //You are not an admin
    }

    if ( !g_Admin ) 
        //There are no admins online!
}