Answers to some simple C# questions I got for an interview

flags.cs

// Each account on a website has a set of access flags that represent a user's access.
// 
// Update and extend the enum so that it contains three new access flags:
//  
//  [Flags]
//  public enum Access
//  {
//    Delete = 1,
//    Publish = 2,
//    Submit = 3,
//    Comment = 4,
//    Modify = 5,
//  }
//  
// 1. A `Writer` access flag that is made up of the `Submit` and `Modify` flags.
// 2. An `Editor` access flag that is made up of the `Delete`, `Publish` and `Comment` flags.
// 3. An `Owner` access that is made up of the `Writer` and `Editor` flags.
// 
// For example, the code below should print "False" as the `Writer` flag does not contain the `Delete` flag.
//
//  `Console.WriteLine(Access.Writer.HasFlag(Access.Delete));`

using System;

namespace Simple2
{
    [Flags]
    public enum Access
    {
        None = 0,
        Delete = 1,
        Publish = 2,
        Submit = 4,
        Comment = 8,
        Modify = 16,
        Writer = Submit | Modify,
        Editor = Delete | Publish | Comment,
        Owner = Writer | Editor,
        
        // 000010 = delete

        // 001000 = submit
        // 100000 = modify
        // 101000 = writer
    }

    public class AccessTest
    {
        public static void Main(string[] args)
        {
            Console.WriteLine(Access.Writer.HasFlag(Access.Delete));
            
            // More examples:
            Console.WriteLine(Access.Writer.HasFlag(Access.Writer));
            Console.WriteLine(Access.Writer.HasFlag(Access.Submit));
        }
    }
}

override.cs

// User interface contains to types of controls: `TextInput`, which accepts all characters and `NumericInput`, which accepts only digits.
//
// Implement the class `TextInput` that contains
// - Public method `void Add(char c)` - adds the given character to the current value
// - Public method `string GetValue()` - returns the current value
//
// Implement the class `NumericInput` that:
// - Inherits `TextInput`
// - Overrides the `Add` method so that each non-numeric character is ignored.
//
// For example, the following code should output "10":
//  TextInput input = new NumericInput();
//  input.Add('1');
//  input.Add('a');
//  input.Add('0');
//  Console.WriteLine(input.GetValue());

using System;

namespace Simple1
{
    public class TextInput
    {
        private string text = @"";

        public virtual void Add(char c)
        {
            text += c;
        }

        public string GetValue()
        {
            return text;
        }
    }

    public class NumericInput : TextInput
    {
        override public void Add(char c)
        {
            if (char.IsNumber(c))
            {
                base.Add(c);
            }
        }
    }

    public class UserInput
    {
        public static void Main(string[] args)
        {
            TextInput input = new NumericInput();
            input.Add('1');
            input.Add('a');
            input.Add('0');
            Console.WriteLine(input.GetValue());
        }
    }
}