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Wildcard string compare (globbing)

By , 15 Feb 2005
 

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

About the Author

Jack Handy
Web Developer
United States United States
No Biography provided

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Comments and Discussions

 
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GeneralC# Direct Portmemberhempels23-Sep-08 15:10 
Well, as direct as I could come up with anyway. Makes use of unsafe to enable pointer arithmetic. Unfortunately, because fixed is required to prevent the GC from moving the pointers, I had to change it to use increment indexers instead of directly manipulating the pointers. Alternatively, you could use stackalloc to instantiate two native char[]'s and copy the values, but that seems contrary to this function's low-memory footprint, high performance goals.
 
Has been tested against every test case presented in the comments section as well as some additional cases I threw in.
 
public unsafe static bool GlobCompare( string glob, string path )
{
      fixed ( char* pGlob = glob, pPath = path )
      {
            int pGlobInc = 0;
            int pPathInc = 0;
 
            int mp = 0;
            int cp = 0;
 
            while ( ( *( pPath + pPathInc ) != 0 ) && ( *( pGlob + pGlobInc ) != '*' ) )
            {
                  if ( ( *( pGlob + pGlobInc ) != *( pPath + pPathInc ) ) && ( *( pGlob + pGlobInc ) != '?' ) )
                  {
                        return false;
                  }
                  pGlobInc++;
                  pPathInc++;
            }
 
            while ( *( pPath + pPathInc ) != 0 )
            {
                  if ( *( pGlob + pGlobInc ) == '*' )
                  {
                        if ( 0 == *( pGlob + ++pGlobInc ) )
                        {
                              return true;
                        }
                        mp = pGlobInc;
                        cp = pPathInc + 1;
                  }
                  else if ( ( *( pGlob + pGlobInc ) == *( pPath + pPathInc ) ) || ( *( pGlob + pGlobInc ) == '?' ) )
                  {
                        pGlobInc++;
                        pPathInc++;
                  }
                  else
                  {
                        pGlobInc = mp;
                        pPathInc = cp++;
                  }
            }
 
            while ( *( pGlob + pGlobInc ) == '*' )
            {
                  pGlobInc++;
            }
            return ( 0 == *( pGlob + pGlobInc ) );
      }
}
General...and yet another C# port [modified]memberDVF27-Aug-10 16:59 
GeneralRe: ...and yet another C# portmemberVUnreal21-Sep-10 11:22 

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