C# How to use the WebClient.DownloadStringAsync Method?

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Hello everyone!
i implemeted C# Get Only Certian Text From Wiki Page?[^] to download all the text from a wiki search( i am using the wiki api to do this) now the problem is that i was using the DownloadString method, and when its called the UI thread freezes up until the string is downloaded(and if the net is slow it will sit there for a while). So in order to solve this i need to use the DownloadStringAsync method but i can't figure out how to use it
here is the original code i am currently using:

C#

public void WikiSearchEngine(string SearchInput)
{
    //Download The Search Page
    var webClient = new WebClient();
    string pageSourceCode = webClient.DownloadString("http://en.wikipedia.org/w/api.php?action=opensearch&search=" + SearchInput);
}

here is what i came up with inorder to try to use the Async version of this method:

C#

public void WikiSearchEngine2(string SearchInput)
{
    //Download The Search Page
    var webClient = new WebClient();
    string StringToConvert = "http://en.wikipedia.org/w/api.php?action=opensearch&search=" + SearchInput;
    Uri StringToUri = new Uri(StringToConvert);
    string pageSourceCode = webClient.DownloadStringAsync(StringToUri);
}

now the problem is that VS gives me an error saying: Cannot implicitly convert type 'void' to 'string'
so what am i doing wrong?
i have already looked at the reference for this method and it didn't really help.
thank you for your help in advance,
MasterCodeon

Posted 9-Jan-15 3:31am

MasterCodeon

Updated 13-Dec-17 9:11am

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DamithSL · Accepted Answer · 2015-01-09T03:39:00

Solution 1

use DownloadStringCompleted [^]event as below

C#

var client = new WebClient();
client.DownloadStringCompleted += (sender, e) =>
{
   string pageSourceCode = e.Result;
   //do something with results 
};

client.DownloadStringAsync(StringToUri);

Posted 9-Jan-15 3:39am

DamithSL

Updated 9-Jan-15 3:40am

v2

Comments

MasterCodeon 9-Jan-15 10:19am

it works great thank you.
i so i guess that the error resulted from me trying to put the contents on what the DownloadStringAsync method's return value(which is void i think) into the string right?
thank you so much!

DamithSL 9-Jan-15 10:20am

yes, correct

MasterCodeon 9-Jan-15 10:31am

ah i understand now.
thank you.