File upload by URI (C #)

In fact, you need to know which way the browser will download the file.

For Internet Explorer, this is done via P / Invoke + Shell32 (stolen from this answer ):

 [DllImport("Shell32.dll")] private static extern int SHGetKnownFolderPath( [MarshalAs(UnmanagedType.LPStruct)]Guid rfid, uint dwFlags, IntPtr hToken, out IntPtr ppszPath); var downloadFolderGuid = new Guid("{374DE290-123F-4565-9164-39C4925E467B}"); IntPtr pathPtr; int result = SHGetKnownFolderPath( downloadFolderGuid, (uint)0x00004000, new IntPtr(0), out pathPtr); if (result >= 0) return Marshal.PtrToStringUni(pathPtr); throw new ExternalException("Unable to retrieve the known folder path. It may not " + "be available on this system.", result); 

(the full code for other cases and the value of constants, see the response by reference)

For other browsers, you will need methods specific to these browsers.

Having a path, you just need to upload the file to the desired path using webClient.DownloadFile :

 using (var c = new WebClient()) c.DownloadFile("http://www.google.com/", Path.Combine(directory, "index.html")); 

Or copy there, if you have everything within the same host:

 File.Copy(@"C:\test.html", Path.Combine(directory, "test.html")); 

I do not understand where the browser is, but using WebClient you can do this:

 using (var client = new WebClient()) { client.DownloadFile(@"C:\source.txt", @"C:\destionation.txt"); } 

The first parameter is loaded from, the second where.

But if you need to work only with local files, then it is better to use another class:

 File.Copy(@"C:\source.txt", @"C:\destionation.txt"); 

UPD:

Download using the default path taken for Internet Explorer (from this answer https://stackoverflow.com/a/24673279/4278250 ):

 String path = String.Empty; RegistryKey rKey = Registry.CurrentUser.OpenSubKey(@"Software\Microsoft\Internet Explorer\Main"); if (rKey != null) path = (String)rKey.GetValue("Default Download Directory"); if (String.IsNullOrEmpty(path)) path = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\downloads"; using (var client = new WebClient()) { client.DownloadFile(@"C:\source.txt", Path.Combine(path, "some file name.txt")); } 

use the browser to download the file as directed by the local address.

If you need to open a file in WebBrowser, you can do this:

 using System.Windows.Forms; var f = new Form(); var b = new WebBrowser() { Parent = f, Dock = DockStyle.Fill }; b.Navigate(@"C:\Temp\test.txt"); f.ShowDialog(); 

UPDATE:

WebClient.DownloadFile (url, path) is intended for downloading files from web servers. If you do not have a web server on your computer or it is disabled or not configured to work with the specified url, then there will be an error.

The browser gets the path to Downloads by reading the value from the registry.

HKEY_CURRENT_USER \Software \Microsoft \Windows \CurrentVersion \Explorer \User Shell Folders {374DE290-123F-4565-9164-39C4925E467B} = %USERPROFILE%\Downloads