获取IP地址 [英] Getting the ip-address

问题描述

在C＃中：

IPHostEntry IPHost = Dns.GetHostEntry(Dns.GetHostName());

for (int i = 0; i < IPHost.AddressList.Length; i++)
{
    textBox1.AppendText("My IP address is: " 
        + IPHost.AddressList[i].ToString() + "\r\n");
}

在此代码中， IPHostEntry 变量包含计算机的所有IP地址。
现在，据我所知，Windows Vista返回的IP地址数量以十六进制表示，以十进制表示，等等。

In this code, the IPHostEntry variable contains all the IP addresses of the computer. Now, as far as I know, Windows vista returns a number of IP addresses some in hexadecimal, some in decimal notation and so on.

问题是所需的十进制表示法会更改其在 IPHostEntry 变量中的位置：最初是在最后一个位置，因此可以使用以下代码访问：

The problem is that the decimal notation which is desired changes its location in the IPHostEntry variable: It initially was occuring in the last location and so could be accessed with the code:

string ipText = IPHost.AddressList[IPHost.AddressList.Length - 1].ToString();

但是，更改计算机的IP地址后，它现在出现在倒数第二个位置，因此需要可以使用以下代码进行访问：

However after changing the IP address of the computer, it now appears in the 2nd last location and so needs to be accessed using the code:

string ipText = IPHost.AddressList[IPHost.AddressList.Length - 2].ToString();

是否有任何代码以十进制表示法检索IP地址，而不管其在<$ c中的位置如何$ c> IPHostEntry 变量？

Is there any code that retrieves the IP addresses in decimal notation irrespective of its location in the IPHostEntry variable??

推荐答案

假设您只需要IPv4地址，当前正在使用此代码（为发布做了一些修改），足以供我使用。只需在结果上调用ToString即可获取地址：

Assuming you only want the IPv4 address, I'm currently using this code (modified a bit for posting) which is robust enough for my use. Just invoke ToString on the result to get the address:

// return the first IPv4, non-dynamic/link-local, non-loopback address
public static IPAddress GetIPAddress()
{
    IPAddress[] hostAddresses = Dns.GetHostAddresses("");

    foreach (IPAddress hostAddress in hostAddresses)
    {
        if (hostAddress.AddressFamily == AddressFamily.InterNetwork &&
            !IPAddress.IsLoopback(hostAddress) &&  // ignore loopback addresses
            !hostAddress.ToString().StartsWith("169.254."))  // ignore link-local addresses
            return hostAddress;
    }
    return null; // or IPAddress.None if you prefer
}

169.254。*部分似乎像黑客一样，但记录在 IETF RFC 3927 。

The 169.254.* part might seem like a hack, but is documented in IETF RFC 3927.

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