像Python中的C＃正则表达式“详细”

Question

In Python, we have the re.VERBOSE argument that allows us to nicely format regex expressions and include comments, such as

import re

ric_index = re.compile(r'''(
    ^(?P<delim>\.)    # delimiter "."
    (?P<root>\w+)$    # Root Symbol, at least 1 character
    )''',re.VERBOSE)

Is there something similar in C#?

Answer 1

Yes, you can have comments in .NET regex.

(examples copied from : https://docs.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-language-quick-reference#miscellaneous_constructs )

You can have inline comments with (?# .... ) :

string regex = @"\bA(?#Matches words starting with A)\w+\b"

or comment to the end of line #

string regex = @"(?x)\bA\w+\b#Matches words starting with A"

And you can always span your regex string on several lines, and use classic C# comments :

string regex = 
    @"\d{1,3}" +        // 1 to 3 digits
    @"\w+" +            // any word characters
    @"\d{10}";          // 10 digits

See also Thomas Ayoub's answer for use of verbatim string @"" on several lines

Answer 2

You can use verbatim string (using @ ), which allow you to write:

var regex = new Regex(@"^(?<delim>\\.)     # delimiter "".""
                    (?<root>\\w+)$    # Root Symbol, at least 1 character
                    ", RegexOptions.IgnorePatternWhitespace);

Note the use of RegexOptions.IgnorePatternWhitespace option to write verbose regexes.