Dictionary及KeyValuePair使用

        /// <summary>
        /// 除去数组中的空值和签名参数并以字母a到z的顺序排序
        /// </summary>
        /// <param name="dicArrayPre">过滤前的参数组</param>
        /// <returns>过滤后的参数组</returns>
        public static Dictionary<string, string> FilterPara(SortedDictionary<string, string> dicArrayPre)
        {
            Dictionary<string, string> dicArray = new Dictionary<string, string>();
            foreach (KeyValuePair<string, string> temp in dicArrayPre)
            {
                if (temp.Key.ToLower() != "sign" && temp.Key.ToLower() != "sign_type" && temp.Value != "" && temp.Value != null)
                {
                    dicArray.Add(temp.Key, temp.Value);
                }
            }

            return dicArray;
        }

        /// <summary>
        /// 把数组所有元素，按照“参数=参数值”的模式用“&”字符拼接成字符串
        /// </summary>
        /// <param name="sArray">需要拼接的数组</param>
        /// <returns>拼接完成以后的字符串</returns>
        public static string CreateLinkString(Dictionary<string, string> dicArray)
        {
            StringBuilder prestr = new StringBuilder();
            foreach (KeyValuePair<string, string> temp in dicArray)
            {
                prestr.Append(temp.Key + "=" + temp.Value + "&");
            }

            //去掉最後一個&字符
            int nLen = prestr.Length;
            prestr.Remove(nLen - , );

            return prestr.ToString();
        }

        /// <summary>
        /// 把数组所有元素，按照“参数=参数值”的模式用“&”字符拼接成字符串，并对参数值做urlencode
        /// </summary>
        /// <param name="sArray">需要拼接的数组</param>
        /// <param name="code">字符编码</param>
        /// <returns>拼接完成以后的字符串</returns>
        public static string CreateLinkStringUrlencode(Dictionary<string, string> dicArray, Encoding code)
        {
            StringBuilder prestr = new StringBuilder();
            foreach (KeyValuePair<string, string> temp in dicArray)
            {
                prestr.Append(temp.Key + "=" + HttpUtility.UrlEncode(temp.Value, code) + "&");
            }

            //去掉最後一個&字符
            int nLen = prestr.Length;
            prestr.Remove(nLen - , );

            return prestr.ToString();
        }

C# get keys and values from List<KeyValuePair<string, string>

    private List<KeyValuePair<string, string>> KV_List = new List<KeyValuePair<string, string>>();
    void initList()
    {
        KV_List.Add(new KeyValuePair<string, string>("qwer", "asdf"));
        KV_List.Add(new KeyValuePair<string, string>("qwer", "ghjk"));
        KV_List.Add(new KeyValuePair<string, string>("zxcv", "asdf"));
        KV_List.Add(new KeyValuePair<string, string>("hjkl", "uiop"));
    }

// #1: get all keys (remove Distinct() if you don't want it)
List<string> allKeys = (from kvp in KV_List select kvp.Key).Distinct().ToList();
// allKeys = { "qwer", "zxcv", "hjkl" }

// #2: get values for a key
string key = "qwer";
List<string> values = (from kvp in KV_List where kvp.Key == key select kvp.Value).ToList();
// values = { "asdf", "ghjk" }

// #3: get keys for a value
string value = "asdf";
List<string> keys = (from kvp in KV_List where kvp.Value == value select kvp.Key).ToList();
// keys = { "qwer", "zxcv" }

https://stackoverflow.com/questions/31414429/c-sharp-get-keys-and-values-from-listkeyvaluepairstring-string

How to insert an item into a key/value pair object?

List<KeyValuePair<string, string>> kvpList = new List<KeyValuePair<string, string>>()
{
    new KeyValuePair<string, string>("Key1", "Value1"),
    new KeyValuePair<string, string>("Key2", "Value2"),
    new KeyValuePair<string, string>("Key3", "Value3"),
};

kvpList.Insert(, new KeyValuePair<string, string>("New Key 1", "New Value 1"));

foreach (KeyValuePair<string, string> kvp in kvpList)
{
    Console.WriteLine(string.Format("Key: {0} Value: {1}", kvp.Key, kvp.Value);
}