代码之家 › 专栏 › 技术社区 › Vivek Shukla

在两个子网之间查找较大的子网(其中一个子网的相邻1较少)

c#-4.0 c#

Vivek Shukla · 技术社区 · 8 年前

我有一个代码片段,可以在两个子网掩码之间找到较大的子网。代码片段使用左移位运算符,IMHO使代码不可读(可能是因为我很少使用它,我相信现在很多开发人员都没有使用它)。

下面是执行此任务的代码。

        IPAddress subNet1 = IPAddress.Parse("255.255.255.0");
        IPAddress subNet2 = IPAddress.Parse("255.255.128.0");

        byte[] bytes;
        bytes = subNet1.GetAddressBytes();
        int tempSub1 = Convert.ToInt32((bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3]));

        bytes = subNet2.GetAddressBytes();
        int tempSub2 = Convert.ToInt32((bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3]));

        if(tempSub1 == tempSub2)
            Console.WriteLine("Pick Any Subnet");

        //Find Larger Subnet(Less number of contiguous 1's)
        if(tempSub1<tempSub2)
            Console.WriteLine("Subnet 1 is Larget Subnet");
        else
            Console.WriteLine("Subnet 2 is Larget Subnet");

我能想到的另一种方法是;为了可读性起见将IP地址转换为二进制,将值存储在字符串中,然后比较1。

有哪些方法可以使代码更易于理解(对于不习惯转换运算符的人)?

2 回复 | 直到 8 年前

ikegami Gilles Quénot 8 年前

这是将字节转换为整数的适当方式。然而 BitConverter 可以掩盖肮脏。

IPAddress subnet1 = IPAddress.Parse("255.255.255.0");
IPAddress subnet2 = IPAddress.Parse("255.255.128.0");

int subnet1Mask = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(subnet1.GetAddressBytes(), 0));
int subnet2Mask = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(subnet2.GetAddressBytes(), 0));

int cmp = -subnet1Mask.CompareTo(subnet2Mask);
if      (cmp < 0) { Console.WriteLine("Subnet 1 is smaller than Subnet 2."); }
else if (cmp > 0) { Console.WriteLine("Subnet 1 is larger than Subnet 2."); }
else              { Console.WriteLine("Subnet 1 and Subnet 2 have the same size."); }

也就是说,您可以简单地比较字节数组,而不是将其转换为整数。

int compareSubnetSize(IPAddress subnet1, IPAddress subnet2)
{
    byte[] subnet1MaskBytes = subnet1.GetAddressBytes();
    byte[] subnet2MaskBytes = subnet2.GetAddressBytes();

    int cmp = 0;
    for (int i=0; i<4; ++i) {
        cmp = subnet1MaskBytes[i].CompareTo(subnet2MaskBytes[i]);
        if (cmp != 0)
            return -cmp;
    }

    return 0;
}

IPAddress subnet1 = IPAddress.Parse("255.255.255.0");
IPAddress subnet2 = IPAddress.Parse("255.255.128.0");

int cmp = compareSubnetSize(subnet1, subnet2);
if      (cmp < 0) { Console.WriteLine("Subnet 1 is smaller than Subnet 2."); }
else if (cmp > 0) { Console.WriteLine("Subnet 1 is larger than Subnet 2."); }
else              { Console.WriteLine("Subnet 1 and Subnet 2 have the same size."); }

Slai 8 年前

将IPv4地址作为字符串进行比较似乎比转换它们更容易。例如:

Regex.Replace("255.255.255.0", @"\d+", m => m.Value.PadLeft(3))       //  "255.255.255.  0"

string.Concat("255.255.255.0".Split('.').Select(s => s.PadLeft(4)))   // " 255 255 255   0"

BitConverter.ToString(IPAddress.Parse("255.255.255.0").GetAddressBytes())  // "FF-FF-FF-00"

string.Concat("255.255.255.0".Split('.').Select(s => $"{int.Parse(s):X2}")))  // "FFFFFF00"