What is a static constructor?

Question

This question was asked to me in an interview:

What is a static constructor?

Does it exist in C++? If yes, please explain it wit

Answer 1

I think static constructor is used to initialize any static data, or to perform a particular action that needs to be performed once only. It is called automatically before the first instance is created or any static members are referenced. In++, we dont have anything called static constructor but you can mimic the functionality of the static constructor. Take a look at this C# static constructor:

public class Bus  {
     // Static variable used by all Bus instances.
     // Represents the time the first bus of the day starts its route.
     protected static readonly DateTime globalStartTime;

     // Property for the number of each bus.
     protected int RouteNumber { get; set; }

     // Static constructor to initialize the static variable.
     // It is invoked before the first instance constructor is run.
     static Bus()
     {
         globalStartTime = DateTime.Now;

         // The following statement produces the first line of output, 
         // and the line occurs only once.
         Console.WriteLine("Static constructor sets global start time to {0}",
             globalStartTime.ToLongTimeString());
     }

     // Instance constructor.
     public Bus(int routeNum)
     {
         RouteNumber = routeNum;
         Console.WriteLine("Bus #{0} is created.", RouteNumber);
     }

     // Instance method.
     public void Drive()
     {
         TimeSpan elapsedTime = DateTime.Now - globalStartTime;

         // For demonstration purposes we treat milliseconds as minutes to simulate
         // actual bus times. Do not do this in your actual bus schedule program!
         Console.WriteLine("{0} is starting its route {1:N2} minutes after global start time {2}.",
                                 this.RouteNumber,
                                 elapsedTime.Milliseconds,
                                 globalStartTime.ToShortTimeString());
     }  }

 class TestBus  {
     static void Main()
     {
         // The creation of this instance activates the static constructor.
         Bus bus1 = new Bus(71);

         // Create a second bus.
         Bus bus2 = new Bus(72);

         // Send bus1 on its way.
         bus1.Drive();

         // Wait for bus2 to warm up.
         System.Threading.Thread.Sleep(25);

         // Send bus2 on its way.
         bus2.Drive();

         // Keep the console window open in debug mode.
         System.Console.WriteLine("Press any key to exit.");
         System.Console.ReadKey();
     }  }  /* Sample output:
     Static constructor sets global start time to 3:57:08 PM.
     Bus #71 is created.
     Bus #72 is created.
     71 is starting its route 6.00 minutes after global start time 3:57 PM.
     72 is starting its route 31.00 minutes after global start time 3:57 PM.      
*/