Click here to Skip to main content
11,707,470 members (81,955 online)
Click here to Skip to main content

Wildcard string compare (globbing)

, 15 Feb 2005 819K 94
Rate this:
Please Sign up or sign in to vote.
Matches a string against a wildcard string such as "*.*" or "bl?h.*" etc. This is good for file globbing or to match hostmasks.

Usage:

This is a fast, lightweight, and simple pattern matching function.

if (wildcmp("bl?h.*", "blah.jpg")) {
  //we have a match!
} else {
  //no match =(
}

Function:

int wildcmp(const char *wild, const char *string) {
  // Written by Jack Handy - <A href="mailto:jakkhandy@hotmail.com">jakkhandy@hotmail.com</A>
  const char *cp = NULL, *mp = NULL;

  while ((*string) && (*wild != '*')) {
    if ((*wild != *string) && (*wild != '?')) {
      return 0;
    }
    wild++;
    string++;
  }

  while (*string) {
    if (*wild == '*') {
      if (!*++wild) {
        return 1;
      }
      mp = wild;
      cp = string+1;
    } else if ((*wild == *string) || (*wild == '?')) {
      wild++;
      string++;
    } else {
      wild = mp;
      string = cp++;
    }
  }

  while (*wild == '*') {
    wild++;
  }
  return !*wild;
}

License

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

Share

About the Author

Jack Handy
Web Developer
United States United States
No Biography provided

You may also be interested in...

Comments and Discussions

 
AnswerMy C# contribution - recursive, of course! Pin
RenniePet26-Mar-10 5:21
memberRenniePet26-Mar-10 5:21 
GeneralRe: My C# contribution - recursive, of course! Pin
Erwin de GRoot29-Mar-10 1:58
memberErwin de GRoot29-Mar-10 1:58 
GeneralDepends on whether you need to optimize the last few nanoseconds out of it... Pin
RenniePet29-Mar-10 7:45
memberRenniePet29-Mar-10 7:45 
GeneralSorry - revised numbers Pin
RenniePet29-Mar-10 8:35
memberRenniePet29-Mar-10 8:35 
GeneralRe: Depends on whether you need to optimize the last few nanoseconds out of it... Pin
Erwin de GRoot29-Mar-10 8:37
memberErwin de GRoot29-Mar-10 8:37 
GeneralYet another version - 25% faster, I think [modified] Pin
RenniePet1-Apr-10 8:24
memberRenniePet1-Apr-10 8:24 
If at first you don't succeed...

Here's my third version, where I say to hell with minimizing lines of code and try to optimize the speed. No "unsafe" code though, unless you consider "goto" to be unsafe coding. Smile | :)

public class MString
{
   /// <summary>
   /// Compare two strings, where strA may contain wildcard characters '*' and '?'.
   /// </summary>
   /// <param name="strA">string which may contain wildcards, may be empty,
   ///                    must not be null</param>
   /// <param name="strB">string to compare to, no wildcard processing, may be empty,
   ///                    must not be null</param>
   /// <param name="ignoreCase">true = ignore upper/lower case, false = observe case</param>
   /// <returns>true = match, false = non-match</returns>
   public static bool CompareWWc(string strA, string strB, bool ignoreCase)
   {
      if (ignoreCase)
         return CompareWWc(strA.ToLower(), strB.ToLower());
      else
         return CompareWWc(strA, strB);
   }
 

   /// <summary>
   /// Compare two strings, where strA may contain wildcard characters '*' and '?'.
   ///
   /// In the comments, the word 'segment' is used to talk about the portions of strA that
   /// fall between two '*' characters, or between the start of the string and the first '*'
   /// or between the last '*' and the end of the string.
   /// </summary>
   /// <param name="strA">string which may contain wildcards, may be empty,
   ///                    must not be null</param>
   /// <param name="strB">string to compare to, no wildcard processing, may be empty,
   ///                    must not be null</param>
   /// <returns>true = match, false = non-match</returns>
   public static bool CompareWWc(string strA, string strB)
   {
      int starPtr = 0;  // Points at the '*' in strA

      // This part of the code handles the first segment in strA, or the case where strA
      //  does not contain any '*' character at all. The first segment is fairly simple to
      //  handle because it must match from the start of strB - no need to have a sliding
      //  match loop.

      // Check strB long enough so we don't need to test for hitting its end while scanning
      if (strB.Length >= strA.Length)
      {
         // Simple optimized scan of first segment of strA and comparison with strB
         for (;; starPtr++)
         {
            if (starPtr == strA.Length)
               return strA.Length == strB.Length;  // No '*' in strA and no mismatch
            if (strA[starPtr] == '*')
               goto firstSegmentMatches;
            if (strA[starPtr] != strB[starPtr] && strA[starPtr] != '?')
               return false;  // Mismatch
         }
      }
      else
      {
         // When strB is shorter than strA a match is not likely. But if strA contains
         //  enough '*' characters it is possible, so we have to give it a try.
         for (;; starPtr++)
         {
            if (strA[starPtr] == '*')
               goto firstSegmentMatches;
            if (starPtr == strB.Length)
               return false;  // No '*' in strA before end of strB encountered
            if (strA[starPtr] != strB[starPtr] && strA[starPtr] != '?')
               return false;  // Mismatch
         }
      }
 
      // The rest of the code handles the case where strA does contain one or more '*'
      //  characters, and the first segment does match the start of strB.

   firstSegmentMatches:
 
      int indexA;  // Start of segment in strA
      int indexB = starPtr;  // Sliding match location in strB

      // Loop to process the segments in strA
      while (true)
      {
         // Test if next segment is last and empty
         indexA = ++starPtr;  // Point past '*'
         if (indexA == strA.Length)
            return true;  // Last segment empty - matches irrespective of strB content

         // Scan over the next segment in strA
         for (;; starPtr++)
            if (starPtr == strA.Length || strA[starPtr] == '*')
               break;
 
         // Try to find match for this segment somewhere in strB
         for (;; indexB++)
         {
            if (starPtr - indexA > strB.Length - indexB)
               return false;  // Mismatch if not enough characters left in strB

            for (int i = indexA, j = indexB; i < starPtr; i++, j++)
               if (strA[i] != strB[j] && strA[i] != '?')
                  goto tryStringBAgain;
 
            goto findNextSegment;  // Match found for this segment in strB

         tryStringBAgain:
            continue;
         }
 
         // Was that last segment? Return if so, loop if not.
      findNextSegment:
         indexB += starPtr - indexA;  // Point past matching portion of strB
         if (starPtr == strA.Length)
            return indexB == strB.Length;  // Return if that was last segment
      }
   }
 
}

And here are my timing results (which I'm not totally sure of, I'm not used to timing code):

My original version:  243 nanoseconds    17 lines of code
Erwin's version:       76 nanoseconds    42 lines of code
My second version:    111 nanoseconds    16 lines of code
My third version:      56 nanoseconds    52 lines of code

I'd appreciate it if someone would check this out and let me know if they find any bugs or anything.
GeneralRe: Yet another version - 25% faster, I think Pin
aleks1k21-Sep-11 2:47
memberaleks1k21-Sep-11 2:47 
QuestionI used this function but I how I can catch variables from the * ??? Pin
moh.hijjawi20-Oct-09 1:55
membermoh.hijjawi20-Oct-09 1:55 
AnswerRe: I used this function but I how I can catch variables from the * ??? Pin
RenniePet1-Apr-10 11:27
memberRenniePet1-Apr-10 11:27 
Questionany updates ? Pin
alhambra-eidos2-Jul-09 5:12
memberalhambra-eidos2-Jul-09 5:12 
GeneralImproved matching with end-of-text Pin
Anders Heie11-May-09 15:20
memberAnders Heie11-May-09 15:20 
GeneralRe: Improved matching with end-of-text: some cases don't work properly! Pin
roadrunner31412-Aug-09 3:35
memberroadrunner31412-Aug-09 3:35 
GeneralRe: Improved matching with end-of-text: some cases don't work properly! Pin
sdiazdiaz20-Jun-13 1:50
membersdiazdiaz20-Jun-13 1:50 
QuestionPathMatchSpec instead? Pin
kintz25-Mar-09 8:55
memberkintz25-Mar-09 8:55 
AnswerRe: PathMatchSpec instead? Pin
MandatoryDefault31-Aug-09 10:39
memberMandatoryDefault31-Aug-09 10:39 
Questionwchar_t version? Pin
rmorales8729-Nov-08 20:16
memberrmorales8729-Nov-08 20:16 
AnswerRe: wchar_t version? Pin
razvar31-Mar-11 21:49
memberrazvar31-Mar-11 21:49 
Generalwildcmp in XBLite Pin
CodeGibbon27-Nov-08 13:56
memberCodeGibbon27-Nov-08 13:56 
GeneralWildcard string compare in C# Pin
haiquang10-Nov-08 22:15
memberhaiquang10-Nov-08 22:15 
GeneralRe: Wildcard string compare in C# Pin
haiquang3-Aug-09 22:22
memberhaiquang3-Aug-09 22:22 
GeneralC# Direct Port Pin
hempels23-Sep-08 15:10
memberhempels23-Sep-08 15:10 
General...and yet another C# port [modified] Pin
DVF27-Aug-10 16:59
memberDVF27-Aug-10 16:59 
GeneralRe: ...and yet another C# port Pin
VUnreal21-Sep-10 11:22
memberVUnreal21-Sep-10 11:22 
GeneralMessage Removed Pin
stonber18-Sep-08 14:22
memberstonber18-Sep-08 14:22 
GeneralUsing in Artistic Style Pin
jimp023-Apr-08 4:43
memberjimp023-Apr-08 4:43 

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

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

| Advertise | Privacy | Terms of Use | Mobile
Web03 | 2.8.150819.1 | Last Updated 15 Feb 2005
Article Copyright 2001 by Jack Handy
Everything else Copyright © CodeProject, 1999-2015
Layout: fixed | fluid