I cannot understand this code inside constructor

Question

  public class Message
  {
      public List<MailboxAddress> To { get; set; }
      public string Subject { get; set; }
      public string Content { get; set; }
      public Message(IEnumerable<string> to, string subject, string content)
      {
          To = new List<MailboxAddress>();
          To.AddRange(to.Select(x => new MailboxAddress("email", x)));
          Subject = subject;
          Content = content;
      }
  }

Answer 1

Hi @prajwal lama,

A constructor is a special method that is used to initialize objects. The advantage of a constructor, is that it is called when an object of a class is created. It can be used to set initial values for fields.

A parameterized constructor can take one or more parameters. Therefore, it can initialize different class objects to different values. This is an advantage over the default constructor.

Code you provided:

First, initialize the Message class. It contains three public variables To, Subject and Content. The parameterized constructorMessage() initializes To, Subject, and Content to the values given in to, subject, and content respectively.

When we call the constructor, we pass the parameters to the constructor Message(IEnumerable<string> to, string subject, string content).

Below I've written a test that calls the constructor and added comments to the code to explain.

using MimeKit;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.ConstrainedExecution;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    internal class Program
    {
        static void Main(string[] args)
        {
            IEnumerable<string> TO = new[] { "test@123.com", "test@456.com" };
            Message message = new Message(TO, "subject", "ABC");
            Console.WriteLine(message.To + " " + message.Subject + " " + message.Content);
        }
        // Create a Message class
        public class Message
        {
            public List<MailboxAddress> To { get; set; }
            public string Subject { get; set; }
            public string Content { get; set; } // Create multiple fields


            public Message(IEnumerable<string> to, string subject, string content) 
            // Create a class constructor with multiple parameters
            {
                To = new List<MailboxAddress>();
                To.AddRange(to.Select(x => new MailboxAddress("email",x)));
                Subject = subject;
                Content = content; // Set the value for To,Subject,Content
            }
        }

    }
}

Best regards,
Lan Huang

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