C#根据IP地址和子网掩码判断子网范围

1、根据IP地址和子网掩码判断子网范围

例如，本地IP为192.168.2.10，子网掩码为255.255.255.0，那么IP的范围：192.168.2.1~192.168.2.254。其中，当一个网段的掩码为255.255.255.0的时候，IP地址的最后一位不可以是255或0。因为这种掩码的网段，最后一位是0的IP是网段的网络地址，而最后一位是255的IP是网段的广播地址，不能分配给主机。

2、IP工具类

 public static class IpAddressUtil
    {
        /// <summary>
        /// 将字符IP转换为Uint
        /// </summary>
        /// <param name="strIp"></param>
        /// <returns></returns>
        public static uint GetIpUintFromString(this string strIp)
        {
            var parts = strIp.Split('.');
            int nIp1 = Convert.ToInt32(parts[0]);
            int nIp2 = Convert.ToInt32(parts[1]);
            int nIp3 = Convert.ToInt32(parts[2]);
            int nIp4 = Convert.ToInt32(parts[3]);
            return (uint)((nIp1 << 24) | (nIp2 << 16) | (nIp3 << 8) | nIp4);
        }
        /// <summary>
        /// 将Uint转换为字符IP
        /// </summary>
        /// <param name="ip"></param>
        /// <returns></returns>
        public static string GetIPStrFromUint(this uint ip)
        {
            byte first = (byte)(ip >> 24);
            byte second = (byte)((ip - (first << 24)) >> 16);
            byte third = (byte)((ip - (second << 16) - (first << 24)) >> 8);
            byte four = (byte)(ip - (second << 16) - (first << 24) - (third << 8));
            return String.Format("{0}.{1}.{2}.{3}", first, second, third, four);
        }

        /// <summary>
        /// 根据输入IP获取最小IP地址
        /// </summary>
        /// <param name="ip"></param>
        /// <returns></returns>
        public static uint GetLowIPStrFromUint(this uint ip)
        {
            byte first = (byte)(ip >> 24);
            byte second = (byte)((ip - (first << 24)) >> 16);
            byte third = (byte)((ip - (second << 16) - (first << 24)) >> 8);
            return (uint)((first << 24) | (second << 16) | (third << 8) | 1);
        }

        /// <summary>
        /// 根据输入IP和子网掩码获取最大IP地址
        /// </summary>
        /// <param name="localIp"></param>
        /// <param name="subNetMask"></param>
        /// <returns></returns>
        public static uint GetMaxIPStrFromUint(this uint localIp, uint subNetMask)
        {
            byte nIp1 = (byte)(localIp >> 24);
            byte nIp2 = (byte)((localIp - (nIp1 << 24)) >> 16);
            byte nIp3 = (byte)((localIp - (nIp2 << 16) - (nIp1 << 24)) >> 8);
            byte nIp4 = (byte)(localIp - (nIp2 << 16) - (nIp1 << 24) - (nIp3 << 8));

            byte subNIp1 = (byte)(subNetMask >> 24);
            byte subNIp2 = (byte)((subNetMask - (subNIp1 << 24)) >> 16);
            byte subNIp3 = (byte)((subNetMask - (subNIp2 << 16) - (subNIp1 << 24)) >> 8);
            byte subNIp4 = (byte)(subNetMask - (subNIp2 << 16) - (subNIp1 << 24) - (subNIp3 << 8));

            int n1 = nIp1 & subNIp1;
            if (n1 == 0) n1 = 255 - subNIp1;
            int n2 = nIp2 & subNIp2;
            if (n2 == 0) n2 = 255 - subNIp2;
            int n3 = nIp3 & subNIp3;
            if (n3 == 0) n3 = 255 - subNIp3;
            int n4 = nIp4 & subNIp4;
            if (n4 == 0) 
             {
               // IP地址的最后一位不可以是255
               if(subNIp4==0)
               {
                 n4 = 254;
               }
               else
               {
                 n4 = 255 - subNIp4;
               }
             }
            return (uint)((n1 << 24) | (n2 << 16) | (n3 << 8) | n4);
        }
    }

3、IP示例

        public static void Test()
        {
            string localIp = "192.168.2.10";
            string subMask = "255.255.255.0";
            uint intLocalIp = localIp.GetIpUintFromString();
            uint intSubMask = subMask.GetIpUintFromString();
            uint intLow = intLocalIp.GetLowIPStrFromUint();
            uint intHigh = intLocalIp.GetMaxIPStrFromUint(intSubMask);
            string strLow = intLow.GetIPStrFromUint();
            string strHigh = intHigh.GetIPStrFromUint();
            Console.WriteLine($"IP地址：{localIp}");
            Console.WriteLine($"子网掩码：{localIp}");
            Console.WriteLine($"IP范围：{strLow}-{strHigh}");
        }

最终输出如下所示：

IP地址：192.168.2.10
子网掩码：192.168.2.10
IP范围：192.168.2.1-192.168.2.255

参考文献：(15条消息) 根据IP地址和子网掩码判断子网范围_hixixi的博客-CSDN博客_子网掩码和ip怎么判断范围