Click here to Skip to main content
13,090,519 members (50,420 online)
Click here to Skip to main content
Add your own
alternative version


63 bookmarked
Posted 6 Sep 2005

Converting Wildcards to Regexes

, 15 Sep 2005
Rate this:
Please Sign up or sign in to vote.
Ever wondered how to do wildcards in C#?


Ever wondered how to do wildcards in .NET? It's not hard, all you have to do is use regular expressions. But it's not always easy to figure it out either. I found that I had to dig around for a while to figure out how to do it properly.

Even though regexes are a lot more powerful, wildcards are still good in situations where you can't expect the user to know or learn the cryptic syntax of regexes. The most obvious example is in the file search functionality of practically all OSs -- there aren't many that don't accept wildcards. I personally need wildcards to handle the HttpHandlers tag in web.config files.

Note: This method is good enough for most uses, but if you need every ounce of performance with wildcards, here is a good place to start.

Using the Code

There are three steps to converting a wildcard to a regex:

  1. Escape the pattern to make it regex-safe. Wildcards use only * and ?, so the rest of the text has to be converted to literals.
  2. Once escaped, * becomes \* and ? becomes \?, so we have to convert \* and \? to their respective regex equivalents, .* and ..
  3. Prepend ^ and append $ to specify the beginning and end of the pattern.

So, here's the golden function:

public static string WildcardToRegex(string pattern)
  return "^" + Regex.Escape(pattern).
  Replace("\\*", ".*").
  Replace("\\?", ".") + "$";

Just to make it look cool, I wrapped it in a Wildcard class that inherits Regex.

/// <summary>
/// Represents a wildcard running on the
/// <see cref="System.Text.RegularExpressions"/> engine.
/// </summary>
public class Wildcard : Regex
 /// <summary>
 /// Initializes a wildcard with the given search pattern.
 /// </summary>
 /// <param name="pattern">The wildcard pattern to match.</param>
 public Wildcard(string pattern)
  : base(WildcardToRegex(pattern))
 /// <summary>
 /// Initializes a wildcard with the given search pattern and options.
 /// </summary>
 /// <param name="pattern">The wildcard pattern to match.</param>
 /// <param name="options">A combination of one or more
 /// <see cref="System.Text.RegexOptions"/>.</param>
 public Wildcard(string pattern, RegexOptions options)
  : base(WildcardToRegex(pattern), options)
 /// <summary>
 /// Converts a wildcard to a regex.
 /// </summary>
 /// <param name="pattern">The wildcard pattern to convert.</param>
 /// <returns>A regex equivalent of the given wildcard.</returns>
 public static string WildcardToRegex(string pattern)
  return "^" + Regex.Escape(pattern).
   Replace("\\*", ".*").
   Replace("\\?", ".") + "$";

You can use it like any other Regex -- case-(in)sensitivity, string replacement, matching and all.

// Get a list of files in the My Documents folder
string[] files = System.IO.Directory.GetFiles(

// Create a new wildcard to search for all
// .txt files, regardless of case
Wildcard wildcard = new Wildcard("*.txt", RegexOptions.IgnoreCase);

// Print all matching files
foreach(string file in files)


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


About the Author

Rei Miyasaka
Canada Canada
The cows are here to take me home now...

You may also be interested in...


Comments and Discussions

PraisePerfect solution Pin
Klixx26-Apr-17 21:09
memberKlixx26-Apr-17 21:09 
QuestionLicense information Pin
Member 103749191-Nov-13 6:43
memberMember 103749191-Nov-13 6:43 
QuestionThanks - just in time Pin
snoopy00116-May-13 4:31
membersnoopy00116-May-13 4:31 
GeneralMy vote of 5 Pin
Christopher Drake2-Jan-13 9:05
memberChristopher Drake2-Jan-13 9:05 
GeneralMy vote of 5 Pin
Member 892678823-Sep-12 23:33
memberMember 892678823-Sep-12 23:33 
QuestionDoes not work with *.* Pin
guest2323113-Sep-12 3:23
memberguest2323113-Sep-12 3:23 
GeneralMy vote of 5 Pin
Kuthuparakkal12-Sep-12 17:03
memberKuthuparakkal12-Sep-12 17:03 
QuestionWord wild card matching behavior a little different from this Pin
weciii2-Mar-12 5:21
memberweciii2-Mar-12 5:21 
Test string:
"she sells sea shells by the sea shore"

Wild card find pattern to type in:

To find in Word:
Open Word 2010 and paste the text.
On the home tab in the far right, select the find drop down and select advanced find. In the resulting dialog type "s*a". Click the more button and check use wildcards. Click find next. It will find "she sells sea" as the first match.

The regex pattern generated for s*a is "^s.*a$"

If you test that regex pattern, it comes back with 0 matches.

The current regex pattern looks like it will only get a match when 's' is at the beginning of the string or line and 'a' is at the end of the string or line.
I'm not too good with regex and could use a solution that would find the pattern anywhere in the string. I've tried a few modifications to the existing regex pattern, but desired result not reached yet.

Found what I was looking for.
Changing the code to the following did the trick:
public static string WildcardToRegex(string pattern)
    return //"^" +
     Replace("\\*", ".*?").
     Replace("\\?", ".");// +"$";

Removed '^', and '$' which says matches need to be at beginning and end of string or line. Changed ".*" to ".*?" - turned 'greedy quantifier' into 'lazy quantifier'. After that, it will still come back with only 2 matches. To compensate for that you could search the string multiple times bumping the start point of the search each time like below:
            Wildcard w = new Wildcard("s*a", RegexOptions.CultureInvariant);
            string s = "she sells sea shells by the sea shore";
            int length = s.Length;
            int index = 0;
            Match m = w.Match(s);
            StringBuilder sb = new StringBuilder();
            bool bsuccess = m.Success;
            while (bsuccess)
                index = s.IndexOf(m.Value, index) + 1;
                if (index < length)
                    m = w.Match(s, index);
                    bsuccess = m.Success;
                    bsuccess = false;

which gives 7 results like Word does:
she sells sea
sells sea
s sea
shells by the sea
s by the sea

modified 5-Mar-12 9:30am.

GeneralMy vote of 5 Pin
vet0n23-Feb-12 21:46
membervet0n23-Feb-12 21:46 
SuggestionAdding More Static Methods Pin
Sina Iravanian14-Dec-11 2:21
memberSina Iravanian14-Dec-11 2:21 
QuestionRe: Adding More Static Methods Pin
DontSailBackwards6-May-13 14:47
memberDontSailBackwards6-May-13 14:47 
AnswerRe: Adding More Static Methods Pin
drzaus1319-Sep-13 4:41
memberdrzaus1319-Sep-13 4:41 
GeneralMy vote of 5 Pin
Nagy Vilmos8-Nov-10 2:24
memberNagy Vilmos8-Nov-10 2:24 
Generalbug?? with '.' Pin
alchemy916-Nov-09 4:07
memberalchemy916-Nov-09 4:07 
GeneralRe: bug?? with '.' Pin
Steve Kutnar2-Sep-10 6:28
memberSteve Kutnar2-Sep-10 6:28 
QuestionHow to add other chars - [A-Z] [modified] Pin
boopathi_tpgit20-Oct-09 2:22
memberboopathi_tpgit20-Oct-09 2:22 
GeneralDifference between httphandlers and httpmodules Pin
gaurav200720-Jun-08 0:20
membergaurav200720-Jun-08 0:20 
GeneralRe: Difference between httphandlers and httpmodules Pin
reinux20-Jun-08 6:24
memberreinux20-Jun-08 6:24 
NewsThere's a new version of the RegEx Tester Tool ! Pin
BucanerO_Slacker1-Mar-08 23:18
memberBucanerO_Slacker1-Mar-08 23:18 
GeneralSmall suggestion Pin
Davide Icardi16-Dec-07 22:12
memberDavide Icardi16-Dec-07 22:12 
GeneralRe: Small suggestion Pin
philippe dykmans31-May-08 15:39
memberphilippe dykmans31-May-08 15:39 
GeneralCorrection... Pin
philippe dykmans31-May-08 15:45
memberphilippe dykmans31-May-08 15:45 
GeneralRe: Correction... Pin
Davide Icardi1-Jun-08 13:19
memberDavide Icardi1-Jun-08 13:19 
GeneralRe: Small suggestion Pin
sssw285-Mar-11 21:25
membersssw285-Mar-11 21:25 
GeneralSimple, yet good Pin
norm .net16-May-07 22:33
membernorm .net16-May-07 22:33 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Permalink | Advertise | Privacy | Terms of Use | Mobile
Web04 | 2.8.170813.1 | Last Updated 15 Sep 2005
Article Copyright 2005 by Rei Miyasaka
Everything else Copyright © CodeProject, 1999-2017
Layout: fixed | fluid