C# .NET apps without Visual Studio

aes.cs

// https://www.c-sharpcorner.com/article/aes-encryption-in-c-sharp/
using System;
using System.IO;
using System.Security.Cryptography;
class ManagedAesSample {
    public static void Main() {
        #if NET40
        Console.WriteLine("Target framework: .NET Framework 4.0");
        #elif NET45  
        Console.WriteLine("Target framework: .NET Framework 4.5");
        #else
        Console.WriteLine("Target framework: .NET Standard 1.4");
        #endif
        Console.WriteLine("Enter text that needs to be encrypted..");
        string data = Console.ReadLine();
        EncryptAesManaged(data);
        Console.ReadLine();
    }
    static void EncryptAesManaged(string raw) {
        try {
            // Create Aes that generates a new key and initialization vector (IV).
            // Same key must be used in encryption and decryption
            using(AesManaged aes = new AesManaged()) {
                // Encrypt string
                byte[] encrypted = Encrypt(raw, aes.Key, aes.IV);
                // Print encrypted string
                Console.WriteLine($"Encrypted data: {System.Text.Encoding.UTF8.GetString(encrypted)}");
                // Decrypt the bytes to a string.
                string decrypted = Decrypt(encrypted, aes.Key, aes.IV);
                // Print decrypted string. It should be same as raw data
                Console.WriteLine($"Decrypted data: {decrypted}");
            }
        } catch (Exception exp) {
            Console.WriteLine(exp.Message);
        }
        Console.ReadKey();
    }
    static byte[] Encrypt(string plainText, byte[] Key, byte[] IV) {
        byte[] encrypted;
        // Create a new AesManaged.
        using(AesManaged aes = new AesManaged()) {
            // Create encryptor
            ICryptoTransform encryptor = aes.CreateEncryptor(Key, IV);
            // Create MemoryStream
            using(MemoryStream ms = new MemoryStream()) {
                // Create crypto stream using the CryptoStream class. This class is the key to encryption
                // and encrypts and decrypts data from any given stream. In this case, we will pass a memory stream
                // to encrypt
                using(CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write)) {
                    // Create StreamWriter and write data to a stream
                    using(StreamWriter sw = new StreamWriter(cs))
                    sw.Write(plainText);
                    encrypted = ms.ToArray();
                }
            }
        }
        // Return encrypted data
        return encrypted;
    }
    static string Decrypt(byte[] cipherText, byte[] Key, byte[] IV) {
        string plaintext = null;
        // Create AesManaged
        using(AesManaged aes = new AesManaged()) {
            // Create a decryptor
            ICryptoTransform decryptor = aes.CreateDecryptor(Key, IV);
            // Create the streams used for decryption.
            using(MemoryStream ms = new MemoryStream(cipherText)) {
                // Create crypto stream
                using(CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read)) {
                    // Read crypto stream
                    using(StreamReader reader = new StreamReader(cs))
                    plaintext = reader.ReadToEnd();
                }
            }
        }
        return plaintext;
    }
}

RubberExample.cs

using System;
using System.Drawing;
using System.Windows.Forms;

public class RubberExample : Form {

	bool mouseDown = false;
	Point mouseDownPoint = Point.Empty;
	Point mousePoint = Point.Empty;

	protected override void OnMouseDown(MouseEventArgs e) {
		base.OnMouseDown(e);
		mouseDown = true;
		mousePoint = mouseDownPoint = e.Location;
	}

	protected override void OnMouseUp(MouseEventArgs e) {
		base.OnMouseUp(e);
		mouseDown = false;
	}

	protected override void OnMouseMove(MouseEventArgs e) {
		base.OnMouseMove(e);
		mousePoint = e.Location;
		Invalidate();
	}

	protected override void OnPaint(PaintEventArgs e) {
		base.OnPaint(e);
		if (mouseDown) {
			Region r = new Region(this.ClientRectangle);
			Rectangle window = new Rectangle(
				Math.Min(mouseDownPoint.X, mousePoint.X),
				Math.Min(mouseDownPoint.Y, mousePoint.Y),
				Math.Abs(mouseDownPoint.X - mousePoint.X),
				Math.Abs(mouseDownPoint.Y - mousePoint.Y)
			);
			r.Xor(window);
			e.Graphics.FillRegion(Brushes.Black, r);
			//Console.WriteLine("Painted: " + window);
		}
	}

	public RubberExample() {
		DoubleBuffered = true;
	}

	public static void Main(String[] args) {
		Application.Run(new RubberExample());
	}
}

test1.cs

// Install command line compiler via NuGet: nuget install Microsoft.Net.Compilers
// csc -out:test1.exe -target:winexe -platform:x64 -debug- -optimize+ test1.cs
// https://stackoverflow.com/a/27093140/1168754

using System;
using System.Drawing;
using System.Windows.Forms;

namespace CSharpGUI {
	public class WinFormExample : Form {
		private Button button;

		public WinFormExample() {
			DisplayGUI();
		}

		private void DisplayGUI() {
			this.Name = "WinForm Example";
			this.Text = "WinForm Example";
			this.Size = new Size(150, 150);
			this.StartPosition = FormStartPosition.CenterScreen;
			button = new Button();
			button.Name = "button";
			button.Text = "Click Me!";
			button.Size = new Size(this.Width - 50, this.Height - 100);
			button.Location = new Point((this.Width - button.Width) / 3, (this.Height - button.Height) / 3);
			button.Click += new System.EventHandler(this.MyButtonClick);
			this.Controls.Add(button);
		}

		private void MyButtonClick(object source, EventArgs e) {
			//MessageBox.Show("My First WinForm Application");
			// Create a new instance of a form.
			Form form1 = new Form();
			// Create two buttons to use as the accept and cancel buttons.
			Button button1 = new Button();
			Button button2 = new Button();
			// Set the text of button1 to "OK".
			button1.Text = "OK";
			// Set the position of the button on the form.
			button1.Location = new Point(10, 10);
			// Set the text of button2 to "Cancel".
			button2.Text = "Cancel";
			// Set the position of the button based on the location of button1.
			button2.Location = new Point(button1.Left, button1.Height + button1.Top + 10);
			// Set the caption bar text of the form.
			form1.Text = "My Dialog Box";
			// Display a help button on the form.
			form1.HelpButton = true;
			// Define the border style of the form to a dialog box.
			form1.FormBorderStyle = FormBorderStyle.FixedDialog;
			// Set the MaximizeBox to false to remove the maximize box.
			form1.MaximizeBox = false;
			// Set the MinimizeBox to false to remove the minimize box.
			form1.MinimizeBox = false;
			// Set the accept button of the form to button1.
			form1.AcceptButton = button1;
			// Set the cancel button of the form to button2.
			form1.CancelButton = button2;
			// Set the start position of the form to the center of the screen.
			form1.StartPosition = FormStartPosition.CenterScreen;
			// Add button1 to the form.
			form1.Controls.Add(button1);
			// Add button2 to the form.
			form1.Controls.Add(button2);
			// Display the form as a modal dialog box.
			form1.ShowDialog();
		}

		public static void Main(String[] args) {
			Application.Run(new WinFormExample());
		}
	}
}

test2.cs

// https://stackoverflow.com/q/8466753/1168754

using System;
using System.Windows.Forms;
using System.ComponentModel;
using System.Drawing;

public class FirstForm : Form
{
  private Label howdyLabel;

  public FirstForm()
  {
    InitializeComponent();
  }

  private void InitializeComponent()
  {
    howdyLabel = new Label();
    howdyLabel.Location = new Point (12, 116);
    howdyLabel.Text = "Howdy, Partner!";
    howdyLabel.Size = new Size (267, 40);
    howdyLabel.AutoSize = true;
    howdyLabel.Font = new Font ("Times New Roman", 26, System.Drawing.FontStyle.Bold);
    //howdyLabel.TabIndex = 0;
    howdyLabel.Anchor  = AnchorStyles.None;
    howdyLabel.TextAlign = ContentAlignment.MiddleCenter;
    Text = "The First Form";
    Controls.Add(howdyLabel);
  }

  public static void Main()
  {
    Application.Run(new FirstForm());
  }
}