How to cancel the execution of a function in C # [closed]

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How to cancel the execution of a function in C # [closed]

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#1 by (1 votes)

1

I'm developing a desktop application in C # WPF where there is a function responsible for sending email EnviarEmail() , when this function is executed it takes a certain amount of time for it to run completely. And when it is being executed the whole form is locked, ie it can not do anything.

How can you make a "Cancel" button that when it is clicked cancel the execution of the EnviarEmail() function and when it is executed it will not be blocked "Cancel button"?

ClickButtonEnviarEmail(){
    EnviarEmail();
}

private void EnviarEmail(){
   .
   . // Enviando Email ~ isso pode demorar um certo tempo, 

 e caso o usuario queira cancelar o envio do email, como é possível
 fazer?
        .
     }

How can this problem be solved?

c# .net email wpf runtime

asked by anonymous 05.07.2017 / 15:49

1 answer

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score 1 · Answer 1

You can do this as shown in documentation . Other than that it would take a fuller library. The example constant there:

using System;
using System.Net;
using System.Net.Mail;
using System.Net.Mime;
using System.Threading;
using System.ComponentModel;
namespace Examples.SmptExamples.Async
{
    public class SimpleAsynchronousExample
    {
        static bool mailSent = false;
        private static void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
        {
            // Get the unique identifier for this asynchronous operation.
             String token = (string) e.UserState;

            if (e.Cancelled)
            {
                 Console.WriteLine("[{0}] Send canceled.", token);
            }
            if (e.Error != null)
            {
                 Console.WriteLine("[{0}] {1}", token, e.Error.ToString());
            } else
            {
                Console.WriteLine("Message sent.");
            }
            mailSent = true;
        }
        public static void Main(string[] args)
        {
            // Command line argument must the the SMTP host.
            SmtpClient client = new SmtpClient(args[0]);
            // Specify the e-mail sender.
            // Create a mailing address that includes a UTF8 character
            // in the display name.
            MailAddress from = new MailAddress("[email protected]", 
               "Jane " + (char)0xD8+ " Clayton", 
            System.Text.Encoding.UTF8);
            // Set destinations for the e-mail message.
            MailAddress to = new MailAddress("[email protected]");
            // Specify the message content.
            MailMessage message = new MailMessage(from, to);
            message.Body = "This is a test e-mail message sent by an application. ";
            // Include some non-ASCII characters in body and subject.
            string someArrows = new string(new char[] {'\u2190', '\u2191', '\u2192', '\u2193'});
            message.Body += Environment.NewLine + someArrows;
            message.BodyEncoding =  System.Text.Encoding.UTF8;
            message.Subject = "test message 1" + someArrows;
            message.SubjectEncoding = System.Text.Encoding.UTF8;
            // Set the method that is called back when the send operation ends.
            client.SendCompleted += new 
            SendCompletedEventHandler(SendCompletedCallback);
            // The userState can be any object that allows your callback 
            // method to identify this send operation.
            // For this example, the userToken is a string constant.
            string userState = "test message1";
            client.SendAsync(message, userState);
            Console.WriteLine("Sending message... press c to cancel mail. Press any other key to exit.");
            string answer = Console.ReadLine();
            // If the user canceled the send, and mail hasn't been sent yet,
            // then cancel the pending operation.
            if (answer.StartsWith("c") && mailSent == false)
            {
                client.SendAsyncCancel();
            }
            // Clean up.
            message.Dispose();
            Console.WriteLine("Goodbye.");
        }
    }
}