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Wildcard string compare (globbing)

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4.90/5 (82 votes)
15 Feb 2005 1.1M   96   144
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

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Comments and Discussions

 
QuestionFastest wildcard function benchmarked with 3 compilers Pin
Sanmayce28-Nov-22 14:55
Sanmayce28-Nov-22 14:55 
QuestionMessage Closed Pin
17-Jun-21 14:45
Dayo Thomas17-Jun-21 14:45 
QuestionUnit tests please Pin
richarno2-Dec-19 22:03
richarno2-Dec-19 22:03 
Suggestionnice algorithm, but with a weakness Pin
senzabandiera7-Oct-16 23:24
senzabandiera7-Oct-16 23:24 
Generaldelphi port Pin
vovach77723-Dec-14 3:38
vovach77723-Dec-14 3:38 
QuestionMy vote of 5+ Pin
Sanmayce29-Nov-13 7:47
Sanmayce29-Nov-13 7:47 
GeneralMy vote of 5 Pin
Franc Morales29-May-13 15:47
Franc Morales29-May-13 15:47 
Questionhelp required for wilcard matching * and # Pin
SaimaAsif23-Feb-12 23:56
SaimaAsif23-Feb-12 23:56 
GeneralMy vote of 5 Pin
Plamen Petrov13-Dec-11 21:37
professionalPlamen Petrov13-Dec-11 21:37 
SuggestionModification with '#' as wildcard joker for digits Pin
Thomas Haase25-Sep-11 23:16
Thomas Haase25-Sep-11 23:16 
QuestionLicence Question Pin
randommark23-Nov-10 0:33
randommark23-Nov-10 0:33 
AnswerAnother C# version, with a twist Pin
Thomas Levesque29-Jun-10 14:50
professionalThomas Levesque29-Jun-10 14:50 
GeneralObscurity Pin
Chuck O'Toole25-Apr-10 18:18
Chuck O'Toole25-Apr-10 18:18 
AnswerMy C# contribution - recursive, of course! Pin
RenniePet26-Mar-10 5:21
RenniePet26-Mar-10 5:21 
GeneralRe: My C# contribution - recursive, of course! Pin
Erwin de GRoot29-Mar-10 1:58
Erwin 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
RenniePet29-Mar-10 7:45 
GeneralSorry - revised numbers Pin
RenniePet29-Mar-10 8:35
RenniePet29-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
Erwin de GRoot29-Mar-10 8:37 
GeneralYet another version - 25% faster, I think [modified] Pin
RenniePet1-Apr-10 8:24
RenniePet1-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
aleks1k21-Sep-11 2:47 
QuestionI used this function but I how I can catch variables from the * ??? Pin
moh.hijjawi20-Oct-09 1:55
moh.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
RenniePet1-Apr-10 11:27 
Questionany updates ? Pin
kiquenet.com2-Jul-09 5:12
professionalkiquenet.com2-Jul-09 5:12 
GeneralImproved matching with end-of-text Pin
Anders Heie11-May-09 15:20
Anders Heie11-May-09 15:20 
GeneralRe: Improved matching with end-of-text: some cases don't work properly! Pin
roadrunner31412-Aug-09 3:35
roadrunner31412-Aug-09 3:35 

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