using System.Text.RegularExpressions; //比如：74B87337454200D4D33F80C4663DC5E5运用它后就变成：74B8-7337-4542-00D4-D33F-80C4-663D-C5E5 string upstr = Regex.Replace(str, @"(\w{4}(?=[^$]))", "$1-");
原文出处：http://www.cnblogs.com/firstcsharp/p/5430778.html
原文：http://www.cnblogs.com/shy1766IT/p/6240270.html