不需要正则表达式
或者，使用 System.Uri 类的内置解析：
foreach (var path in new [] { @"C:\foo\bar\", @"\\server\bar" })
{
var uri = new Uri(path);
if (uri.IsUnc)
{
Console.WriteLine("Connects to host '{0}'", uri.Host);
}
else
{
Console.WriteLine("Local path");
}
}
打印：
本地路径
连接到主机“服务器”
如果你想匹配扩展，不要重新发明轮子，使用Path.GetExtension：
var path = "\\some\really long and complicated path\foo.txt";
var extensionOfPath = Path.GetExtension(path);
if (string.Equals(".txt", extensionOfPath, StringComparison.CurrentCultureIgnoreCase))
{
Console.WriteLine("It's a txt");
}
else
{
Console.WriteLine("It's a '{0}', which is not a txt", extensionOfPath);
}
一般来说，我试图建议您在解决问题时避免跳到正则表达式。首先问问自己是否有人为您解决了问题 (example for HTML)。关于为什么正则表达式在CodingHorror 和（不太严重）on xkcd 上的代表不好的原因有很好的讨论。
正则表达式版本
如果您一心想使用 Regex，我认为这不是工作的最佳工具，它可以完成。使用间距和 cmets 确保您的代码可读。
string input = @"\\Apple-butter27\AliceFakePlace\SomeDay\Grand100\Some File Name Stuff\Yes these are fake words\One more for fun2000343\myText.txt";
Regex regex = new Regex(@"
^
(?:
# if server is present, capture to a named group
# use a noncapturing group to remove the surrounding slashes
# * is a greedy match, so it will butt up against the following directory search
# this group may or may not occur, so we allow either this or the drive to match (|)
(?:\\\\(?<server>[^\\]*)\\)
# if there is no server, then we best have a drive letter
|(?:(?<drive>[A-Z]):\\)
)
# then we have a repeating group (+) to capture all the directory components
(?:
# each directory is composed of a name (which does not contain \\)
# followed by \\
(?<directory>[^\\]*)\\
)+
# then we have a file name, which is identifiable as we already ate the rest of
# the string. So, it is just all non-\\ characters at the end.
(?<file>[^\\]*)
$", RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);
var matches = regex.Match(input).Groups;
foreach (var group in regex.GetGroupNames())
{
Console.WriteLine("Matched {0}:", group);
foreach (var value in matches[group].Captures.Cast<Capture>())
{
Console.WriteLine("\t{0}", value.Value);
}
}
打印
Matched server:
Apple-butter27
Matched drive:
Matched directory:
AliceFakePlace
SomeDay
Grand100
Some File Name Stuff
Yes these are fake words
One more for fun2000343
Matched file:
myText.txt
我现在只是猜测......
听起来你有某种应用程序，它调用它所在的目录并在其下构建多层结构。类似于以下内容：
C:\
root directory for the application\
site name\
date of work\
project name\
bar\
actual.txt
files.txt
你是否在寻找实际的文件，我不知道。无论哪种方式，我们都知道C:\root directory\ 并认为它可能有实际文件。然后我们可以获取目录树并枚举以找到实际的文件：
var diRoot = new DirectoryInfo(@"C:\drop");
var projectDirectories = FindProjects(diRoot);
// get all of the files in all of the project directories of type .txt
var projectFiles = projectDirectories.SelectMany(di => di.GetFiles("*.txt"));
// projectFiles now contains:
// actual.txt
// files.txt
private static IEnumerable<DirectoryInfo> FindProjects(DirectoryInfo cDir, int depth = 0)
{
foreach (var di in cDir.GetDirectories())
{
// assume projects are three levels deep
if (depth == 3)
{
// it's a project, so we can return it
yield return di;
}
else
{
// pass it through, return the results
foreach (var d in FindProjects(di, depth + 1))
yield return d;
}
}
}
而且由于我们不对路径进行字符串操作，因此我们可以透明地处理本地和 UNC 路径。