子网地址与广播地址的算法

子网地址的算法：用IP地址 AND 子网掩码

                 IP地址与子网掩码进行和运算.

广播地址的算法：( NOT 子网掩码)   OR   IP地址

                 子网掩码进行非运算的结果再与IP地址进行或运算。

 

class function TConvertUtil.SubnetRange(AIpMask, AIpStart: string;
  var ARefIpStart, ARefIpEnd: string): Boolean;
var
  ASubNetIpLong,ABroadCastIpLong:LongWord;
  AStartLong,AEndLong:LongWord;
begin
  Result := True;

  ASubNetIpLong := FCnIp.IPToInt(AIpMask) and FCnIp.IPToInt(AIpStart);
  
  ABroadCastIpLong := (not FCnIp.IPToInt(AIpMask)) or FCnIp.IPToInt(AIpStart);

  AStartLong := ASubNetIpLong + 1;
  AEndLong := ABroadCastIpLong - 1;

  ARefIpStart := FCnIp.IntToIP(AStartLong);
  ARefIpEnd := FCnIp.IntToIP(AEndLong);
end;

 

initialization
  FCnIp := TCnIp.Create(nil);
finalization
  FCnIp.Free;