微信支付MD5签名算法C#版，ASCII码字典序排序0,A,B,a,b

        /// <summary>
        /// 微信支付MD5签名算法，ASCII码字典序排序0,A,B,a,b
        /// </summary>
        /// <param name="InDict">待签名名键值对</param>
        /// <param name="TenPayV3_Key">用于签名的Key</param>
        /// <returns>MD5签名字符串</returns>
        public static string WePaySign(IDictionary<string, string> InDict, string TenPayV3_Key)
        {
            string[] arrKeys = InDict.Keys.ToArray();
            Array.Sort(arrKeys, string.CompareOrdinal);  //参数名ASCII码从小到大排序；0,A,B,a,b;

            var StrA = new StringBuilder();

            foreach (var key in arrKeys)
            {
                string value = InDict[key]; 
                if (!String.IsNullOrEmpty(value)) //空值不参与签名
                {
                    StrA.Append(key + "=")
                       .Append(value + "&");
                }
            }
            
            //foreach (var item in InDict.OrderBy(x => x.Key))//参数名字典序；0,A,a,B,b;
            //{
            //    if(!String.IsNullOrEmpty(item.Value)) //空值不参与签名
            //    {
            //        StrA.Append(item.Key + "=")
            //           .Append(item.Value + "&");
            //    }
            //}

            StrA.Append("key=" + TenPayV3_Key); //注：key为商户平台设置的密钥key
            return StrFormat.GetMd5Hash(StrA.ToString()).ToUpper();
        }