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Wildcard string compare (globbing)

, 15 Feb 2005
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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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About the Author

Jack Handy
Web Developer
United States United States
No Biography provided

Comments and Discussions

 
Generalmp and cp Pinmembertwopieman15-Mar-05 11:59 
GeneralRe: mp and cp Pinmemberradboudp16-Feb-07 1:14 
In case you are matching something like the following:
 
"*.abc" to "ab.de.abc"
 
In the second loop it looks for the first character after the asterisk that is the same in the string. At first it matches "*" against "ab". mp = ".abc" during this. Now wild = ".abc" and string = ".de.abc". Obvious no match. On the next loop the first characters do match (both '.') and wild becomes "abc" and string "de.abc". The next loop there is no match and it falls to the else. Here it resets wild to the last mp (mask pattern??) and string to the last cp (character pattern) WITHOUT THE FIRST CHARACTER. (It actually advances cp one position.)
 
Why does it do this. After matching the * against part of the string and encountering a possible poisiton where to match the remainder of the pattern, it continued comparing characters from both to each other. This fialed. Since right before the position of mp there was a *, it is still allowed to add characters to the part that is matched against that. Basically, it goes back to that position but decides that the character that occurs in both strings is not the next character in the pattern but part of the '*' wildcard.
 
In the end it has matched '*' with 'ab.de'.

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