Matching strings with wildcard

Question

I would like to match strings with a wildcard (*), where the wildcard means "any". For example:

*X = string must end with X X* = string must start with X *X* = string must contain X 

Also, some compound uses such as:

*X*YZ* = string contains X and contains YZ X*YZ*P = string starts with X, contains YZ and ends with P. 

Is there a simple algorithm to do this? I'm unsure about using regex (though it is a possibility).

To clarify, the users will type in the above to a filter box (as simple a filter as possible), I don't want them to have to write regular expressions themselves. So something I can easily transform from the above notation would be good.

Answer 1

Often, wild cards operate with two type of jokers:

  ? - any character  (one and only one)   * - any characters (zero or more) 

so you can easily convert these rules into appropriate regular expression:

// If you want to implement both "*" and "?" private static String WildCardToRegular(String value) {   return "^" + Regex.Escape(value).Replace("\\?", ".").Replace("\\*", ".*") + "$";  }  // If you want to implement "*" only private static String WildCardToRegular(String value) {   return "^" + Regex.Escape(value).Replace("\\*", ".*") + "$";  } 

And then you can use Regex as usual:

  String test = "Some Data X";    Boolean endsWithEx = Regex.IsMatch(test, WildCardToRegular("*X"));   Boolean startsWithS = Regex.IsMatch(test, WildCardToRegular("S*"));   Boolean containsD = Regex.IsMatch(test, WildCardToRegular("*D*"));    // Starts with S, ends with X, contains "me" and "a" (in that order)    Boolean complex = Regex.IsMatch(test, WildCardToRegular("S*me*a*X"));