Asp.net 4.0 C# : Twitter Search Api Getting error 401 unauthorized

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C#

API

twitter

WebAPI

ASP.NET4

I want to get tweets list from #tag using any API in Asp.net 4.0 C#. I have tried using bellow code. I am getting 401 unauthorized error in GetResponse().

My Code :

string url = "https://api.twitter.com/1.1/search/tweets.json?q=#Haylof";
string oauthconsumerkey = "consumer key";
string oauthtoken = "oauth token";
string oauthconsumersecret = "consumer secret";
string oauthtokensecret = "oauth token secret";
string oauthsignaturemethod = "HMAC-SHA1";
string oauthversion = "1.0";
string oauthnonce = Convert.ToBase64String(
  new ASCIIEncoding().GetBytes(DateTime.Now.Ticks.ToString()));
TimeSpan timeSpan = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
string oauthtimestamp = Convert.ToInt64(timeSpan.TotalSeconds).ToString();
SortedDictionary<string, string> basestringParameters = new SortedDictionary<string, string>();
basestringParameters.Add("q", "#Haylof");
basestringParameters.Add("oauth_version", oauthversion);
basestringParameters.Add("oauth_consumer_key", oauthconsumerkey);
basestringParameters.Add("oauth_nonce", oauthnonce);
basestringParameters.Add("oauth_signature_method", oauthsignaturemethod);
basestringParameters.Add("oauth_timestamp", oauthtimestamp);
basestringParameters.Add("oauth_token", oauthtoken);
//Build the signature string
StringBuilder baseString = new StringBuilder();
baseString.Append("GET" + "&");
baseString.Append(EncodeCharacters(Uri.EscapeDataString(url.Split('?')[0]) + "&"));
foreach (KeyValuePair<string, string> entry in basestringParameters)
{
    baseString.Append(EncodeCharacters(Uri.EscapeDataString(entry.Key + "=" + entry.Value + "&")));
}

//Remove the trailing ambersand char last 3 chars - %26
string finalBaseString = baseString.ToString().Substring(0, baseString.Length - 3);

//Build the signing key
string signingKey = EncodeCharacters(Uri.EscapeDataString(oauthconsumersecret)) + "&" +
EncodeCharacters(Uri.EscapeDataString(oauthtokensecret));

//Sign the request
HMACSHA1 hasher = new HMACSHA1(new ASCIIEncoding().GetBytes(signingKey));
string oauthsignature = Convert.ToBase64String(
  hasher.ComputeHash(new ASCIIEncoding().GetBytes(finalBaseString)));

//Tell Twitter we don't do the 100 continue thing
ServicePointManager.Expect100Continue = false;

//authorization header
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(@url);
StringBuilder authorizationHeaderParams = new StringBuilder();
authorizationHeaderParams.Append("OAuth ");
authorizationHeaderParams.Append("oauth_nonce=" + "\"" + Uri.EscapeDataString(oauthnonce) + "\",");
authorizationHeaderParams.Append("oauth_signature_method=" + "\"" + Uri.EscapeDataString(oauthsignaturemethod) + "\",");
authorizationHeaderParams.Append("oauth_timestamp=" + "\"" + Uri.EscapeDataString(oauthtimestamp) + "\",");
authorizationHeaderParams.Append("oauth_consumer_key=" + "\"" + Uri.EscapeDataString(oauthconsumerkey) + "\",");
if (!string.IsNullOrEmpty(oauthtoken))
    authorizationHeaderParams.Append("oauth_token=" + "\"" + Uri.EscapeDataString(oauthtoken) + "\",");
authorizationHeaderParams.Append("oauth_signature=" + "\"" + Uri.EscapeDataString(oauthsignature) + "\",");
authorizationHeaderParams.Append("oauth_version=" + "\"" + Uri.EscapeDataString(oauthversion) + "\"");
webRequest.Headers.Add("Authorization", authorizationHeaderParams);

webRequest.Method = "GET";
webRequest.ContentType = "application/x-www-form-urlencoded";

//Allow us a reasonable timeout in case Twitter's busy
webRequest.Timeout = 3 * 60 * 1000;
try
{
    HttpWebResponse webResponse = webRequest.GetResponse() as HttpWebResponse;
    Stream dataStream = webResponse.GetResponseStream();
    // Open the stream using a StreamReader for easy access.
    StreamReader reader = new StreamReader(dataStream);
    // Read the content.
    string responseFromServer = reader.ReadToEnd();
}
catch (Exception ex)
{
}

I am not expert.Please Help me out.Thanks!