Regular expression

Question

What should be the regular expression for
<something>_<something else>.xml

I am trying below but It doesn't return any matched for valid pattern.

Regex.Matches(file.Name, @"^.[a-z0-9][_][a-z0-9].[Xx][Mm][Ll]$")

Answer 1

This way should work too:

Regex.Matches(file.Name, "[a-z0-9]+_([a-z0-9]+[_-])*[a-z0-9]+[.]xml$", RegexOptions.IgnoreCase);  

Since the suffix may be uppercase or lowercase, you need to use the Regex.Matches overload with RegexOptions as a parameter.

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Answer 2

Theoretically, “something” can be expressed with “.+”, but it seems that you only accept letters and digits, therefore try this expression:

(?i)^[a-z0-9]+_[a-z0-9]+[.]xml$

If you need something special, then explain the rules and show examples.

(To insert the code try using the "101" button, because your expression is probably distorted).

Answer 3

For your new details, try this expression:

Regex.Matches(file.Name, @"(?i)^(?! )[^\x00-\x1F\\/.*?:<>""|]+_[a-z0-9-]+[.]xml$")

You can adjust it to allow the valid '.' inside the names.