C# Static Constructor (with Examples)

Last updated on March 21st, 2023 at 12:39 pm

A static constructor is a method that initializes static data members of a class or executes a specific task that needs to be done only once. This constructor is automatically invoked before the first instance of a class is created, or any static data members are accessed.

In this post, We will learn about the C# static constructor with multiple examples.

Syntax

The examples below will show you how to declare static constructor syntax without any parameters or access modifiers.

 // Creating a class
    public class Customer
    {
        // Creating a static constructor
        static Customer()
        {
            // Code that needs to be execute only once.
         }
    }

Characteristics of Static constructor in C#:

A static constructor in C# has the following characteristics.

C# Static constructor example

Following is an example of a static constructor in C#.

using System;
namespace StaticConstructorExample
{  
    // Customer class
    public class Customer
    {
       // Static Constructor
      static  Customer()
        {
            Console.WriteLine("Static constructor executed !");         
        }

        //Default constructor

       public Customer()
        {
            Console.WriteLine("Default constructor executed !");
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
         // Here, Static and instance constructors
        // will invoke for the first instance

            Customer customer1 = new Customer();

          // Here only default constructor will invoke not the static constructor.
            Customer customer2 = new Customer();
            Console.ReadLine();
        } 
    }
    /* Output:
     Static constructor executed !
     Default constructor executed !
     Default constructor executed !
     */
}

Output:

In the above example, the Static constructor gets invoked only once at the time of the first object creation of the Customer class.
For the next object creation, only the default constructor will be called.

Note: If you don’t provide a static constructor in a class to initialize static fields or variables, the C# compiler will initialize static fields to default values.

5 Scenarios Where Static Constructors Are Useful in C#

Here are some scenarios where you might want to use a static constructor in C#:

1. Initializing static fields or properties: You can use a static constructor to initialize static fields or properties of a class. It is useful when you have some values that need to be set before any instances of the class are created.
2. Loading configuration files or resources: You can use a static constructor to load configuration files or other resources your class needs to function. It ensures that the resources are loaded before any instances of the class are created.
3. Registering events or services: You can use a static constructor to register events or services your class needs to interact with. A static constructor can be useful when you want to ensure that these events or services are registered before any instances of the class are created.
4. Enforcing class invariants: You can use a static constructor to enforce class invariants, such as ensuring that specific fields have valid values or that some constraints are met.
5. Initializing unmanaged resources: You can use a static constructor to initialize unmanaged resources, such as opening a file or initializing a database connection. It ensures that the resources are available before any instances of the class are created.

Overall, static constructors are useful when you want to ensure that some initialization code is executed before any instances of a class are created.

FAQs

Following are some frequently asked questions and answers about Static constructor in C#:

References MSDN: Constructors

Summary:

In this article, we learned about the static constructor in C# with examples. I hope you enjoyed this post and found it useful. In case you have any doubts, please post your feedback, question, or comments below.

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Shekh Ali

Meet Sheikh Ali, a skilled Software engineer and passionate a blogger. He enjoys sharing his expertise in C#, Java, SQL, Design Patterns, and other related topics through his writing. When he's not coding, Sheikh Ali can often indulge in his passions for reading books and fitness training.

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