string s = @"<Data ss:Type=""String"">{1}</Data>";var txt = Regex.Replace(s, @"ss:type=""String""(?=>\{1\})",@"ss:Type=""Number""", RegexOptions.IgnoreCase);
正则表达式零宽度正预测先行断言?=
原文：http://www.cnblogs.com/slmk/p/6366443.html
