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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 
Hi Erwin,

Thanks for your posting. It did make me decide to investigate the situation.

I still really think this is a situation that begs for recursion. But maybe you were right that substring is not a good idea. So I made this version:

public class MString2
{
   /// <summary>
   /// Function to compare two strings, where strA may contain wildcard characters '*' and
   /// '?'. http://en.wikipedia.org/wiki/Wildcard_character
   /// </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 = don't ignore 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(), 0, strB.ToLower(), 0);
      else
         return CompareWWc(strA, 0, strB, 0);
   }


   /// <summary>
   /// Function to compare two strings, where strA may contain wildcard characters '*' and
   /// '?'. http://en.wikipedia.org/wiki/Wildcard_character
   /// </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)
   {
      // Just call the private recursive version of this function
      return CompareWWc(strA, 0, strB, 0);
   }


   /// <summary>
   /// Private recursive function used by the above two public functions.
   /// </summary>
   /// <param name="strA">string which may contain wildcards, may be empty, must not be null</param>
   /// <param name="indexA">index into strA marking start of the string for processing purposes</param>
   /// <param name="strB">string to compare to, no wildcard processing, may be empty, must not be null</param>
   /// <param name="indexB">index into strB marking start of the string for processing purposes</param>
   /// <returns>true = match, false = non-match</returns>
   private static bool CompareWWc(string strA, int indexA, string strB, int indexB)
   {
      // Top of loop to scan across strA (and strB)
      for (int i = 0; indexA + i < strA.Length; i++)
      {
         // Special processing when we hit a '*' in strA
         if (strA[indexA + i] == '*')
         {
            // If the '*' is at the end of strA then result = true irrespective of strB
            if (indexA + i == strA.Length - 1)
               return true;

            // Do recursive calls to try to find a match somewhere to the right in strB
            for (int j = indexB + i; j < strB.Length; j++)
               if (CompareWWc(strA, indexA + i + 1, strB, j))
                  return true;
            return false;
         }

         // Normal processing for non-'*' characters in strA
         if (indexB + i >= strB.Length || (strA[indexA + i] != strB[indexB + i] && strA[indexA + i] != '?'))
            return false;
      }

      // We've reached the end of strA and there is no '*' in strA
      return strA.Length - indexA == strB.Length - indexB;
   }

}


Then I ran some timing tests, using System.Diagnostics.Stopwatch. I put my test case with 19 calls to the function in a loop and executed it 10,000 times. I did this for my original version, your version, and my new version. I compiled the programs in Release mode.

Assuming I haven't made a mistake somewhere, here are my results for a single function call:

My original version:  342 nonoseconds
Your version:         237 nanoseconds
My second version:    279 nanoseconds

Now to tell you the truth, I find it very difficult to get excited about saving 100 nanoseconds at the expense of having two and a half times as many lines of code. Especially since my expected use of this function in my application will probably never exceed a couple hundred calls per day. Smile | :)

Anyway, thanks for getting me to think things over again and make the tests. Personally, at least in this particular case, I prefer programmer understandability to execution efficiency. I've decided to stick with my original version, since I think my second version is more difficult to understand, and the improved efficiency not worth that disadvantage.
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 
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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