在C#中添加到列表时的IP地址异常 [英] IP address exception when adding to a list in C#

问题描述

我正在尝试从文本文件中读取一组IP，并将其添加到IPAddress类型列表中.在"listIPAdrrs.Add(IPAddress.Parse(list [i]));"行上引发了异常.

I am trying to read a set of IPs from a text file and add it to a IPAddress type list. An exception is raised on the line "listIPAdrrs.Add(IPAddress.Parse(list[i]));"

例外是

指定了无效的IP地址.

An invalid IP address was specified.

      List<string> list = new List<string>();
        string text = System.IO.File.ReadAllText(@"D:\ips.txt");

        String[] str = text.Split('\n');

        for (int j = 0; j < str.Length; j++)
        {
            list.Add(str[j]);
        }

        List<IPAddress> listIPAdrrs = new List<IPAddress>();

        for (int i = 0; i < list.Count; i++)
        {
             //Console.WriteLine(list[i]);

            listIPAdrrs.Add(IPAddress.Parse(list[i]));
        }

推荐答案

问题是，行尾不一定只是\n(在Windows中，很可能是\r\n)，并且IP地址后面是IPAddress.Parse认为\r字符不是有效的IP地址.

The problem is that line endings are not necessarily just a \n (on Windows, it's most likely \r\n), and an IP address followed by the \r character isn't considered a valid IP address by IPAddress.Parse.

幸运的是，进行CLR的人员认为这一切并得到了一些非常强大的代码，因此我们将改用File.ReadAllLines.

Fortunately, the guys who made the CLR thought it all out and got some pretty robust code, so we're going to use File.ReadAllLines instead.

List<string> list = new List<string>(System.IO.File.ReadAllLines(@"D:\ips.txt"));
List<IPAddress> listIPAdrrs = new List<IPAddress>();

for (int i = 0; i < list.Count; i++)
{
    //Console.WriteLine(list[i]);
    listIPAdrrs.Add(IPAddress.Parse(list[i]));
}

如果这是您的事，您还可以使用LINQ使其更短(尽管您失去了使用TryParse的能力):

If that's your kind of thing, you can also use LINQ to make it even shorter (though you lose the ability to use TryParse doing it):

List<IPAddress> listIPAdrrs = System.IO.File.ReadAllLines(@"D:\ips.txt")
    .Select(line => IPAddress.Parse(line))
    .ToList();

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