There must always be at least 2 constructors. A default one and a parameterized one c# code example

Example 1: c# constructor

public class Person
{
   private string last;
   private string first;

   public Person(string lastName, string firstName)
   {
      last = lastName;
      first = firstName;
   }

   // Remaining implementation of Person class.
}

Example 2: how to start a constructer c#

public static void Main()
{