C# 正则表达式提取url指定参数值

 /// <summary>
        /// 获取url字符串参数，返回参数值字符串
        /// </summary>
        /// <param name="name">参数名称</param>
        /// <param name="url">url字符串</param>
        /// <returns></returns>
        public string GetQueryString(string name,string url)
        {          
            System.Text.RegularExpressions.Regex re = new System.Text.RegularExpressions.Regex(@"(^|&)?(\w+)=([^&]+)(&|$)?", System.Text.RegularExpressions.RegexOptions.Compiled);
            System.Text.RegularExpressions.MatchCollection mc = re.Matches(url);
            foreach (System.Text.RegularExpressions.Match m in mc)
            {
                if (m.Result("$2").Equals(name))
                {
                    return m.Result("$3");
                }               
            }
            return "";
        }