public interface IFilesService
    {
        DirectoryInfo GetDirectoryInfo(string directoryPath);
        void DeleteFile(string fileName);
        void WritePersonInFile(string fileName,string name, string lastName, byte age);
    }

    class FilesServices:IFilesService
    {
        public DirectoryInfo GetDirectoryInfo(string directoryPath)
        {
            return new DirectoryInfo(directoryPath);
        }

        public void DeleteFile(string fileName)
        {
            File.Delete(fileName);
            Console.WriteLine("the file has been deleted");
        }

        public void WritePersonInFile(string fileName, string name, string lastName, byte age)
        {
            var text = $"my name is {name} {lastName} with {age} years old from dotnettips.info";
            File.WriteAllText(fileName,text);
        }    
    }

    class FilesServicesProxy:IFilesService
    {
        private readonly IFilesService _filesService;

        public FilesServicesProxy()
        {
            _filesService=new FilesServices();
        }

        public DirectoryInfo GetDirectoryInfo(string directoryPath)
        {
            var existing = Directory.Exists(directoryPath);
            if (!existing)
                Directory.CreateDirectory(directoryPath);
            return _filesService.GetDirectoryInfo(directoryPath);
        }

        public void DeleteFile(string fileName)
        {
            if(!File.Exists(fileName))
                Console.WriteLine("Please enter a valid path");
            else
                _filesService.DeleteFile(fileName);
        }

        public void WritePersonInFile(string fileName, string name, string lastName, byte age)
        {
            if (!Directory.Exists(fileName.Remove(fileName.LastIndexOf("\\"))))
            {
                Console.WriteLine("File Path is not valid");
                return;
            }
            if (name.Trim().Length == 0)
            {
                Console.WriteLine("first name must enter");
                return;
            }

            if (lastName.Trim().Length == 0)
            {
                Console.WriteLine("last name must enter");
                return;
            }

            if (age<18)
            {
                Console.WriteLine("your age is illegal");
                return;
            }


            if (name.Trim().Length < 3)
            {
                Console.WriteLine("first name must be more than 2 letters");
                return;
            }

            if (lastName.Trim().Length <5)
            {
                Console.WriteLine("last name must be more than 4 letters");
                return;
            }

            _filesService.WritePersonInFile(fileName,name,lastName,age);
            Console.WriteLine("the file has been written");
        }
    }

static void Main(string[] args)
        {
            IFilesService filesService=new FilesServicesProxy();
            filesService.WritePersonInFile("c:\\myfakepath\\a.txt","ali","yeganeh",26);

            var directory = filesService.GetDirectoryInfo("d:\\myrightpath\\");
            var fileName = Path.Combine(directory.FullName, "dotnettips.txt");

            filesService.WritePersonInFile(fileName, "al", "yeganeh", 26);
            filesService.WritePersonInFile(fileName, "ali", "yeganeh", 12);
            filesService.WritePersonInFile(fileName, "ali", "yeganeh", 26);

            filesService.DeleteFile("c:\\myfakefile.txt");
            filesService.DeleteFile(fileName);
        }

File Path is not valid
first name must be more than 2 letters
your age is illegal
the file has been written
Please enter a valid path
the file has been deleted

    <div id="coursesSection" class="k-rtl k-header">
        <div class="box-col">
            <form id="myForm" data-role="validator" novalidate="novalidate">
                <h3>ثبت نام</h3>
                <ul>
                    <li>
                        <label for="Id">Id</label>
                        <span id="Id" data-bind="text:course.Id"></span>
                    </li>
                    <li>
                        <label for="UserName">نام</label>
                        <input type="text" id="UserName" name="UserName" class="k-textbox"
                               data-bind="value:course.UserName"
                               required />
                    </li>
                    <li>
                        <label for="CourseName">دوره</label>
                        <input type="text" dir="ltr" id="CourseName" name="CourseName" required
                               data-bind="value:course.CourseName" />
                        <span class="k-invalid-msg" data-for="CourseName"></span>
                    </li>
                    <li>
                        <label for="Credit">مبلغ پرداختی</label>
                        <input id="Credit" name="Credit" type="number" min="1000" max="6000"
                               required data-max-msg="عددی بین 1000 و 6000" dir="ltr"
                               data-bind="value:course.Credit"
                               class="k-textbox k-input" />
                        <span class="k-invalid-msg" data-for="Credit"></span>
                    </li>
                    <li>
                        <label for="Email">پست الکترونیک</label>
                        <input type="email" id="Email" dir="ltr" name="Email"
                               data-bind="value:course.Email"
                               required class="k-textbox" />
                    </li>
                    <li>
                        <label for="Tel">تلفن</label>
                        <input type="tel" id="Tel" name="Tel" dir="ltr" pattern="\d{8}"
                               required class="k-textbox"
                               data-bind="value:course.Tel"
                               data-pattern-msg="8 رقم" />
                    </li>
                    <li>
                        <input type="checkbox" name="Accept"
                               data-bind="checked:accepted"
                               required />
                        شرایط دوره را قبول دارم.
                        <span class="k-invalid-msg" data-for="Accept"></span>
                    </li>
                    <li>
                        <button class="k-button"
                                data-bind="enabled: accepted, click: doSave"
                                type="submit">
                            ارسال
                        </button>
                        <button class="k-button" data-bind="click: resetModel">از نو</button>
                    </li>
                </ul>
                <span id="doneMsg"></span>
            </form>
        </div>

    <div id="coursesSection" class="k-rtl k-header">
        <div class="box-col">
            <form id="myForm" data-role="validator" novalidate="novalidate">
                           <!--فرم بحث شده در ابتدای مطلب-->
            </form>
        </div>
        <div id="results">
            <table class="metrotable">
                <thead>
                    <tr>
                        <th>Id</th>
                        <th>نام</th>
                        <th>دوره</th>
                        <th>هزینه</th>
                        <th>ایمیل</th>
                        <th>تلفن</th>
                        <th></th>
                        <th></th>
                    </tr>
                </thead>
                <tbody data-template="row-template" data-bind="source: coursesDataSourceRows"></tbody>
                <tfoot data-template="footer-template" data-bind="source: this"></tfoot>
            </table>
            <script id="row-template" type="text/x-kendo-template">
                <tr>
                    <td data-bind="text: Id"></td>
                    <td data-bind="text: UserName"></td>
                    <td dir="ltr" data-bind="text: CourseName"></td>
                    <td>
                        #: kendo.toString(get("Credit"), "c0") #
                    </td>
                    <td data-bind="text: Email"></td>
                    <td data-bind="text: Tel"></td>
                    <td><button class="k-button" data-bind="click: deleteCourse">حذف</button></td>
                    <td><button class="k-button" data-bind="click: editCourse">ویرایش</button></td>
                </tr>
            </script>
            <script id="footer-template" type="text/x-kendo-template">
                <tr>
                    <td colspan="3"></td>
                    <td>
                        جمع کل: #: kendo.toString(totalPrice(), "c0") #
                    </td>
                    <td colspan="2"></td>
                    <td></td>
                    <td></td>
                </tr>
            </script>
        </div>
    </div>

• لیست محصولات فروخته شده
  
• درصد کمیسیون خام
  
• تاریخ فروش
  
• شعبه فروش
  
• نوع پرداخت 
  

@{
    ViewBag.Title = "Index";
}
<h2>
    Index</h2>
<fieldset>
    <legend>HandleForm1 (Normal)</legend>
    @using (Html.BeginForm(actionName: "HandleForm1", controllerName: "Home"))
    {
        @:your favorite tech: <br />
        @Html.RadioButton(name: "tech", value: ".NET", isChecked: true) @:DOTNET <br />
        @Html.RadioButton(name: "tech", value: "JAVA", isChecked: false) @:JAVA <br />
        @Html.RadioButton(name: "tech", value: "PHP", isChecked: false) @:PHP <br />
        <input type="submit" value="Submit" />
    }
</fieldset>

using System.Collections.Generic;
using System.Web.Mvc;

namespace MvcApplication23.Controllers
{
    public class HomeController : Controller
    {
        [HttpGet]
        public ActionResult Index()
        {
            return View();
        }

        [HttpPost]
        public ActionResult HandleForm1(string tech)
        {
            return RedirectToAction("Index");
        }
    }
}

@helper RadioButtonList(string groupName, IEnumerable<System.Web.Mvc.SelectListItem> items)
{
    <div class="RadioButtonList">
        @foreach (var item in items)
        {
            @item.Text
            <input type="radio" name="@groupName"
                   value="@item.Value"
                   @if (item.Selected) { <text>checked="checked"</text> }
               />
            <br />
        }
    </div>
}

using System.Collections.Generic;
using System.Web.Mvc;

namespace MvcApplication23.Controllers
{
    public class HomeController : Controller
    {
        [HttpGet]
        public ActionResult Index()
        {
            ViewBag.Tags = new[]
                            {
                                new SelectListItem { Text = ".NET", Value = "Val1", Selected = true },
                                new SelectListItem { Text = "JAVA", Value = "Val2", Selected = false },
                                new SelectListItem { Text = "PHP", Value = "Val3", Selected = false }
                            };
            return View();
        }

        [HttpPost]
        public ActionResult HandleForm2(string preferredTechnology)
        {
            return RedirectToAction("Index");
        }
    }
}

@{
    ViewBag.Title = "Index";
}
<h2>
    Index</h2>

<fieldset>
    <legend>HandleForm2 (Helper)</legend>
    @using (Html.BeginForm(actionName: "HandleForm2", controllerName: "Home"))
    {
        @:your favorite tech: <br />
        @Helpers.RadioButtonList("preferredTechnology", (SelectListItem[])ViewBag.Tags)
        <input type="submit" value="Submit" />
    }
</fieldset>

using System.ComponentModel.DataAnnotations;

namespace MvcApplication23.Models
{
    public enum Gender
    {
        [Display(Name = "مرد")]
        Male,
        [Display(Name = "زن")]
        Female,
    }

    public class User
    {
        [ScaffoldColumn(false)]
        public int Id { set; get; }

        [Display(Name = "نام")]
        public string Name { set; get; }

        [Display(Name = "جنسیت")]
        [UIHint("EnumRadioButtonList")]
        public Gender Gender { set; get; }
    }
}

@using System.ComponentModel.DataAnnotations
@using System.Globalization
@model Enum
@{
    Func<Enum, string> getDescription = enumItem =>
    {
        var type = enumItem.GetType();
        var memInfo = type.GetMember(enumItem.ToString());
        if (memInfo != null && memInfo.Any())
        {
            var attrs = memInfo[0].GetCustomAttributes(typeof(DisplayAttribute), false);
            if (attrs != null && attrs.Any())
                return ((DisplayAttribute)attrs[0]).GetName();
        }
        return enumItem.ToString();
    };

    var listItems = Enum.GetValues(Model.GetType())
                        .OfType<Enum>()
                        .Select(enumItem =>
                                    new SelectListItem()
                                    {
                                        Text = getDescription(enumItem),
                                        Value = enumItem.ToString(),
                                        Selected = enumItem.Equals(Model)
                                    });

    string prefix = ViewData.TemplateInfo.HtmlFieldPrefix;    
    ViewData.TemplateInfo.HtmlFieldPrefix = string.Empty;

    int index = 0;
    foreach (var li in listItems)
    {
        string fieldName = string.Format(CultureInfo.InvariantCulture, "{0}_{1}", prefix, index++);
    <div class="editor-radio">
        @Html.RadioButton(prefix, li.Value, li.Selected, new { @id = fieldName })
        @Html.Label(fieldName, li.Text)
    </div>
    }

    ViewData.TemplateInfo.HtmlFieldPrefix = prefix;
}

using System.Collections.Generic;
using System.Web.Mvc;
using MvcApplication23.Models;

namespace MvcApplication23.Controllers
{
    public class HomeController : Controller
    {
        [HttpGet]
        public ActionResult Index()
        {
            var user = new User { Id = 1, Name = "name 1", Gender = Gender.Male };
            return View(user);
        }

        [HttpPost]
        public ActionResult HandleForm3(User user)
        {
            return RedirectToAction("Index");
        }
    }
}

@model MvcApplication23.Models.User
@{
    ViewBag.Title = "Index";
}
<h2>
    Index</h2>
<fieldset>
    <legend>HandleForm3 (EditorForModel)</legend>
    @using (Html.BeginForm(actionName: "HandleForm3", controllerName: "Home"))
    {
        @Html.EditorForModel()
        <input type="submit" value="Submit" />
    }
</fieldset>

@Html.EditorFor(model => model.EnumProperty, "EnumRadioButtonList")

No type was specified for the decimal column 'Price' on entity type 'Movie'. 
This will cause values to be silently truncated if they do not fit in the default precision and scale.

public class Movie
{
    public int ID { get; set; }

    [Column(TypeName = "decimal(18, 2)")]
    public decimal Price { get; set; }
}

protected override void OnModelCreating(ModelBuilder builder)
{
    base.OnModelCreating(builder);

    foreach (var property in builder.Model.GetEntityTypes()
                                    .SelectMany(t => t.GetProperties())
                                    .Where(p => p.ClrType == typeof(decimal)
                                                || p.ClrType == typeof(decimal?)))
    {
       property.SetColumnType("decimal(18, 6)");
    }
}

var firstControllerObj = function ($scope) {
    // Initialize the model object
    $scope.firstModelObj = {
        firstName: "John"
    };
};

var secondControllerObj = function ($scope) {
    // Initialize the model object
    $scope.secondModelObj = {
        lastName: "Doe"
    };

    // Define utility functions
    $scope.getFullName = function () {
        return $scope.firstModelObj.firstName + " " +
          $scope.secondModelObj.lastName;
    };
};

var thirdControllerObj = function ($scope) {
    // Initialize the model object
    $scope.thirdModelObj = {
        middleName: "Al",
        lastName: "Smith"
    };

    // Define utility functions
    $scope.getFullName = function () {
        return $scope.firstModelObj.firstName + " " +
          $scope.thirdModelObj.middleName + " " +
          $scope.thirdModelObj.lastName;
    };
};

    <div ng-controller="firstControllerObj">
        <h3>First controller</h3>
        <strong>First name:</strong> {{firstModelObj.firstName}}<br />
        <br />
        <label>Set the first name: <input type="text" ng-model="firstModelObj.firstName" /></label><br />
        <br />
        
        
        <div ng-controller="secondControllerObj">
            <h3>Second controller (inside First)</h3>
            <strong>First name (from First):</strong> {{firstModelObj.firstName}}<br />
            <strong>Last name (from Second):</strong> {{secondModelObj.lastName}}<br />
            <strong>Full name:</strong> {{getFullName()}}<br />
            <br />
            <label>Set the first name: <input type="text" ng-model="firstModelObj.firstName" /></label><br />
            <label>Set the last name: <input type="text" ng-model="secondModelObj.lastName" /></label><br />
            <br />
            

            <div ng-controller="thirdControllerObj">
                <h3>Third controller (inside Second and First)</h3>
                <strong>First name (from First):</strong> {{firstModelObj.firstName}}<br />
                <strong>Middle name (from Third):</strong> {{thirdModelObj.middleName}}<br />
                <strong>Last name (from Second):</strong> {{secondModelObj.lastName}}<br />
                <strong>Last name (from Third):</strong> {{thirdModelObj.lastName}}<br />
                <strong>Full name (redefined in Third):</strong> {{getFullName()}}<br />
                <br />
                <label>Set the first name: <input type="text" ng-model="firstModelObj.firstName" /></label><br />
                <label>Set the middle name: <input type="text" ng-model="thirdModelObj.middleName" /></label><br />
                <label>Set the last name: <input type="text" ng-model="thirdModelObj.lastName" /></label>
            </div>
        </div>
    </div>

@viewModel DotvvmDemo.CalculatorViewModel, Dotvvm
    
<p>
    Enter the first number: 
    <dot:TextBox Text="{value: Number1}" />
</p>
<p>
    Enter the second number: 
    <dot:TextBox Text="{value: Number2}" />
</p>
<p>
    <dot:Button Text="Calculate" Click="{command: Calculate()}" />
</p>
<p>
    The result is: {{value: Result}}
</p>

using System;
    
namespace DotvvmDemo 
{
    public class CalculatorViewModel 
    {
            
        public int Number1 { get; set; }
            
        public int Number2 { get; set; }
            
        public int Result { get; set; }
            
        public void Calculate() 
        {
            Result = Number1 + Number2;
        }
    }
}