正则表达式_日期匹配

 c#里完美.   貌似在vb里不行,在VB程序里试了一下而已,不确定.

 public string FiltrationDateString(string str)//过滤
        {
            string result = "";
            string pattern = @"\d{4}(?<connectchar>[-/.])((1[0-2])|(0?\d))\k<connectchar>(([12]\d)|(3[01])|(0?\d))";
            Regex reg = new Regex(pattern);
            var matchs = reg.Matches(str);
            int sum = 0;
            for (int i = 0; i < matchs.Count; i++)
            {
                Match match = matchs[i];
                if (i == matchs.Count - 1)
                {
                    result += match.Value;
                    break;
                }
                result += (match.Value + "&");
            }
            return result;
        }