Add User To SharePoint Group Programmatically

In this article I am going to explain how we can add a user in SharePoint 2010 site programmatically. Here we have a Site Url and Group already define in that site. Below is the code to show to add user in SharePoint group:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint; 

namespace ADD_User
{
    class Program
    {
        static void Main(string[] args)
        {
            string FileUrl = string.Empty;
           string Member = string.Empty;
            string Visitor = string.Empty;
            string UserName = string.Empty;
            string Email;
            string UserType;
            string UserEmail = string.Empty; 

            SPGroup spGroup = null; 

            try
            {
                FileUrl = "http://localhost:1000/"; 

                //Already Define Group
                Member = "DotNetCodesgSite Members";
                Visitor = "DotNetCodesgSite Visitors"; 

                UserType = "Admin";
                UserName = "Rahul";

                //Open Site
                SPSite spSite = new SPSite(FileUrl);
                SPWeb spWeb = spSite.OpenWeb();
 

                /////For getting user details//////////////////////

                SPUser user = spWeb.EnsureUser(UserName);
                SPListItem list = spWeb.SiteUserInfoList.Items.GetItemById(user.ID);
                int user_id = int.Parse(user.ID.ToString());
                Console.WriteLine("User Name=" + UserName);
                Email = user.Email;
                UserName = user.Name;
                Console.WriteLine("User Email=" + Email);
                Console.WriteLine("UserName=" + UserName);
                //////////////////////////////////////////////////                
 
                if (UserType == "Admin")
                {
                    //Open group
                    spGroup = spWeb.SiteGroups[Member];
                }
                else if (UserType == "Visitor")
                {
                    //Open group
                    spGroup = spWeb.SiteGroups[Visitor];
                }
 
                //Add and update group with new user
                if (!UserName.Contains(@"\"))
                {
                    string domain = "MyDomain";
                    UserName = domain + UserName;
                }
 
                spGroup.AddUser(UserName, UserEmail, UserName, "Added by UserControl");
                spGroup.Update();

                string ErrorMessage = "Success in Adding user in SharePoint Site.";
                string ErrorCode = "Success";
                Console.Read();
            }
            catch (Exception ex)
            { 

                string ErrorMessage = ex.Message.ToString();
                string ErrorCode = "Failed";
                Console.WriteLine(ex.Message.ToString());
                Console.Read();
            }
            finally
            {
                //spWeb.Close();
                //spSite.Close();
            }
 
        }
    }
}