Adding proxy proxies to WebClient in C #

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usingSystem; usingSystem.Collections.Generic; usingSystem.ComponentModel; usingSystem.Data; usingSystem.Drawing; usingSystem.Linq; usingSystem.Net; usingSystem.Text; usingSystem.Windows.Forms; namespaceTestproxy { Public Partial classMainform:form { PublicMainForm () {InitializeComponent (); }            Private voidBtndownload_click (Objectsender, EventArgs e) {              Try{Start (); }              Catch(Exception ex) {MessageBox.Show (ex).              Message); }          }            Private voidStart () {txtresult.clear (); varClient =NewWebClient (); varURI =NewUri (TxtUrl.Text.Trim ()); Client. Downloadstringcompleted+=client_downloadstringcompleted; Client. Encoding=Encoding.UTF8; if(checkbox.checked) {varProxy =Createproxy (); if(Proxy = =NULL)return; Client. Proxy=proxy; } client.          DownloadStringAsync (URI); }            Private voidclient_DownloadStringCompleted (Objectsender, DownloadStringCompletedEventArgs e) {              Try{Txtresult.text=E.result; }              Catch(Exception ex) {varmsg =Ex.                  Message; if(ex. InnerException! =NULL) msg =Ex.                  Innerexception.message;              MessageBox.Show (msg); }          }            Private voidCheckBox_CheckedChanged (Objectsender, EventArgs e) {gbproxy.enabled=checkbox.checked; }            PrivateWebProxy Createproxy () {varHost =TxtHost.Text.Trim (); if(string. Isnullorwhitespace (host)) {MessageBox.Show ("Please enter a proxy address"); return NULL; }              varPort =0; Try{Port=Convert.ToInt32 (TxtPort.Text.Trim ()); }              Catch(Exception) {MessageBox.Show ("Please enter the correct proxy port"); return NULL; }              varCRE =NewNetworkCredential (txtUsername.Text, Txtpwd.text); varProxy =NewWebProxy (TxtHost.Text.Trim (), port) {Credentials =CRE}; returnproxy; }      }  }  

Adding proxy proxies to WebClient in C #