无法将类型隐式转换为system.net

Question

I am having an error in my program when trying to download files from a remote server, I am using the System.Net Lib and it is having an issue converting to it.

I am getting the error Message

Cannot implicitly convert type 'System.ComponentModel.AsyncCompletedEventHandler' to System.Net.DownloadProgressChangedEventHandler'

on the last line in the code block

AsyncCompletedEventHandler(client_DownloadFileCompleted);

Error Line ^

Form.cs V

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;

namespace Buildcraft_Installer
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void btnStartDownload_Click(object sender, EventArgs e)
        {
            prgDownload.Visible = true;
                WebClient client = new WebClient();
                client.DownloadProgressChanged += new
                DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
                client.DownloadProgressChanged += new
                AsyncCompletedEventHandler(client_DownloadFileCompleted);

I would be very grateful if anyone had a way to resolve this or a workaround to get the same result, thanks :)

Answer 1

You probably meant to write client.DownloadFileCompleted on your last line.

You currently have two calls to DownloadProgressChanged , one with a matching delegate type ( DownloadProgressChangedEventHandler ), one with the wrong one ( AsyncCompletedEventHandler ).

Answer 2

You use incorrect delegate in subscription to the event on last line.

If you use Visual Studio, write += and press Tab key, so the method with correct signature will be generated.

But I see that a couple of lines above you already subscribed to the same event, so my impression is that you don't use a correct event for that what you want to achieve.

There should be DownloadFileCompleted event. I presume that is what you want.