forward Float:fGetDistanceBetweenPlayers(player1, player2);
stock Float:fGetDistanceBetweenPlayers(player1, player2)
{
      new Float:x, Float:y, Float:z;
      if(!IsPlayerConnected(player1) || !IsPlayerConnected(player2)) return -1.00;
      GetPlayerPos(player1, x, y, z);
      return GetPlayerDistanceFromPoint(player2, x, y, z);
}

printf("Расстояние = %f", fGetDistanceBetweenPlayers(playerid, giveplayerid));