Code:
#define IsPlayer(%1) ( 1 <= %1 <= g_iMaxPlayers )
In hlds , players get a number (id). This id can be 1,2, ..., max players (32 is max on HLDS).
So, this function check if iKiller (id) is player and not something else (fall, world , etc).
Than to write
Code:
if( 1 <= iKiller <= g_iMaxPlayers )
, with this function can write
Code:
if( IsPlayer( iKiller ) )
.
You understand

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