An introduction to C#

using System;

public class Class1
{
    string greeting1 = "Hello world!";
    public Class1() => Console.WriteLine(Greeting1);
    public string Greeting1 { get => greeting1; set => greeting1 = value; }
    const int numeral1 = 12345;
    public Class1() => Console.WriteLine(numeral1);
    double numeral2 = 1.5;
    bool bool1 = true;
    string userName = Console.ReadLine();
    char greeting2 = "hi";
}