regex - Regular Expression to search overlapping pattern -

this simplified version of problem:

i'm trying extract letters surrounded non-word characters regex doesn't work when non-characters overlap.

here's code:

var text = "z#a#b#s"; var regex = new regex(@"\w(?<letter>\w)\w"); foreach (var m in regex.matches(text).cast<match>()) {     console.writeline("match = {0}", m.value);     console.writeline("letter = {0}", m.groups["letter"].value);     console.writeline("-------------------"); } 

i expected match both , b instead matches a. here's output:

match = #a# letter = ------------------- 

this work text "z#a##b#s" (there's no overlap between 2 matches).

how can extract both , b text "z#a#b#s"?

thanks

use behind , ahead

        var text = "z#a#b#s";         var regex = new regex(@"(?<=\w)\w(?=\w)");         foreach (match m in regex.matches(text))         {             console.writeline("letter = {0}", m.value);             console.writeline("-------------------");         } 

http://www.regular-expressions.info/lookaround.html