Why when downloading files the second file when downloading the speed label show the infinity sign?

Question

In the screenshot the Download Speed = show the infinity sign kb/s instead the speed.

The first downloading file it's showing fine the speed but then from the second it's showing the infinity sign. How can I fix it so it will show the speed for each file ?

The downloading method :

private async Task DownloadAsync()  
        {  
            using (var client = new WebClient())  
            {  
                client.DownloadFileCompleted += (s, e) => lblStatus.Text = "Download File Completed.";  
                client.DownloadFileCompleted += (s, e) => sw.Reset();  
                client.DownloadProgressChanged += (s, e) => progressBar1.Value = e.ProgressPercentage;  
                client.DownloadProgressChanged += (s, e) => lblAmount.Text = FormatBytes(e.BytesReceived);  
                client.DownloadProgressChanged += (s, e) => lblSpeed.Text = string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00"));  
                client.DownloadProgressChanged += (s, e) => lblDownloadSize.Text = Convert.ToInt64(client.ResponseHeaders["Content-Length"]).ToString();  
                client.DownloadProgressChanged += (s, e) =>  
                {  
                    lblDownloadProgress.Text = "%" + e.ProgressPercentage.ToString();  
                    lblDownloadProgress.Left = Math.Min(  
                        (int)(progressBar1.Left + e.ProgressPercentage / 100f * progressBar1.Width),  
                        progressBar1.Width - lblDownloadProgress.Width  
                    );  
                };  
                for (int i = 0; i < urls.Count; i++)  
                {  
                    await client.DownloadFileTaskAsync(new Uri(urls[i]), @"d:\satImages\img" + i + ".gif");  
                }  
            }  
        }  

Format bytes method :

private string FormatBytes(long bytes)  
        {  
            string[] Suffix = { "B", "KB", "MB", "GB", "TB" };  
            int i;  
            double dblSByte = bytes;  
            for (i = 0; i < Suffix.Length && bytes >= 1024; i++, bytes /= 1024)  
            {  
                dblSByte = bytes / 1024.0;  
            }  
  
            return String.Format("{0:0.00} {1}", dblSByte, Suffix[i]);  
        }  

And in a button click event starting it :

private async void btnStart_Click(object sender, EventArgs e)  
        {  
            lblStatus.Text = "Downloading...";  
            sw.Start();  
            await DownloadAsync();  
        }  

Answer 1

Hi ShalvaGabriel-1621,

The whole process of the stopwatch is:

1. reset
2. start
3. stop

You did not stop and reset the stopwatch after the first download.

After modification：

   private async Task DownloadAsync() {  
       using (var client = new WebClient()) {  
           client.DownloadFileCompleted += (s, e) => lblStatus.Text = "Download File Completed.";  
           client.DownloadProgressChanged += (s, e) => progressBar1.Value = e.ProgressPercentage;  
           client.DownloadProgressChanged += (s, e) => lblAmount.Text = FormatBytes(e.BytesReceived);  
           client.DownloadProgressChanged += (s, e) => lblSpeed.Text = string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00"));  
           client.DownloadProgressChanged += (s, e) => lblDownloadSize.Text = Convert.ToInt64(client.ResponseHeaders["Content-Length"]).ToString();  
           client.DownloadProgressChanged += (s, e) =>  
           {  
               lblDownloadProgress.Text = "%" + e.ProgressPercentage.ToString();  
               lblDownloadProgress.Left = Math.Min(  
                   (int)(progressBar1.Left + e.ProgressPercentage / 100f * progressBar1.Width),  
                   progressBar1.Width - lblDownloadProgress.Width  
               );  
           };  
           for (int i = 0; i < urls.Count; i++) {  
               sw.Reset();  
               sw.Start();  
               await client.DownloadFileTaskAsync(new Uri(urls[i]), @"d:\satImages\img" + i + ".gif");  
               client.DownloadFileCompleted += (s, e) => sw.Stop();  
           }  
       }  
   }  



   private async void BtnStart_Click(object sender, EventArgs e) {  
       lblStatus.Text = "Downloading...";  
       await DownloadAsync();  
   }  

Output:

Best regards,
Jiale Xue

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