C# 0 The Complete Reference

Static Constructors

A constructor can also be specified as 

static

. A 

static

 constructor is typically used to 

initialize features that apply to a class rather than an instance. Thus, it is used to initialize 

aspects of a class before any objects of the class are created. Here is a simple example:

// Use a static constructor.

using System;

class Cons {

  public static int alpha;

  public int beta;

  // A static constructor.

  static Cons() {

    alpha = 99;

    Console.WriteLine("Inside static constructor.");

  }

  // An instance constructor.

  public Cons() {

    beta = 100;

    Console.WriteLine("Inside instance constructor.");

  }

}

class ConsDemo {

  static void Main() {

    Cons ob = new Cons();

    Console.WriteLine("Cons.alpha: " + Cons.alpha);

    Console.WriteLine("ob.beta: " + ob.beta);

  }

}

Here is the output:

Inside static constructor.

Inside instance constructor.

Cons.alpha: 99

ob.beta: 100

Notice that the 

static

 constructor is called automatically (when the class is first loaded) and 

before the instance constructor. This can be generalized. In all cases, the 

static

 constructor 

will be executed before any instance constructor. Furthermore, 

static

 constructors cannot 

have access modifiers (thus, they use default access) and cannot be called by your program.

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