C# Situation in which you should use static class

We will learn about the situations in which you should use static variable in C# class.

In C#, a static class is a class that cannot be instantiated and can only contain static members, such as static methods, static properties, static fields, and static events. 

If there are shared data and functionality which are independent of any object then all such data and functionality can be encapsulated inside static class. If data is not going to change during the lifetime of application, that data can be labelled as static data. Or if a single instance of class is enough to live throughout the life of application then static class maybe okay.

Here are a few scenarios where you might use a static class:

1. Utility Classes: Static classes are often used to create utility classes that provide helper functions or methods that can be used throughout an application. For example, a MathHelper class that contains static methods for common mathematical operations like calculating square roots or logarithms.

    public static class MathHelper
    {
        public static double SquareRoot(double value)
        {
            return Math.Sqrt(value);
        }
    }
 

2. Constants and Configuration: When you have constants or configuration values that are the same for all instances of a class and do not change during the lifetime of the application, you can use a static class to hold these values.

    public static class AppConfig
    {
        public static readonly string ApiBaseUrl = "https://api.example.com";
    }
 

3. Logging: A static logger class can be used to log messages throughout the application without needing to create instances of a logger.

    public static class Logger
    {
        public static void Log(string message)
        {
            // Implementation to log the message
        }
    }
 

4. Singleton Pattern: Static classes can be used to implement the singleton pattern, ensuring that only one instance of a class is created throughout the application.

    public sealed class Singleton
    {
        private static readonly Singleton instance = new Singleton();

        private Singleton() { }

        public static Singleton Instance => instance;

        // Other members and functionality
    }
 

These situations demonstrate when using a static class in CSharp can be appropriate for encapsulating functionality or data that is shared across the application and does not require instantiation or multiple instances.