Static Classes in C#

What are Static Classes in C#?

A Static Class in C# is a class that cannot be instantiated. It contains only static members and is used to group related utility functions, constants, and helper methods.

Key Features of Static Classes

• Cannot be instantiated (no objects can be created).
• Contains only static members (methods, properties, and fields).
• Cannot have constructors (except a private static constructor).
• Provides efficient, globally accessible methods without object instantiation.

Example: Creating and Using a Static Class

The following example demonstrates how to declare and use a static class.

Example: Static Class in C#

public static class MathUtilities
{
    public static double Square(double number)
    {
        return number * number;
    }

    public static double Cube(double number)
    {
        return number * number * number;
    }
}

// Usage
class Program
{
    static void Main()
    {
        Console.WriteLine(MathUtilities.Square(5)); // Output: 25
        Console.WriteLine(MathUtilities.Cube(3));   // Output: 27
    }
}
        

The MathUtilities static class provides utility methods Square() and Cube() without requiring instantiation.

Static Constructors in Static Classes

A static class can have a static constructor that initializes static fields when the class is first accessed.

Example: Static Constructor in a Static Class

public static class Logger
{
    public static string LogFilePath { get; }

    // Static Constructor
    static Logger()
    {
        LogFilePath = "C:\\Logs\\logfile.txt";
        Console.WriteLine("Static constructor executed.");
    }

    public static void Log(string message)
    {
        Console.WriteLine($"Logging: {message}");
    }
}

// Usage
class Program
{
    static void Main()
    {
        Console.WriteLine(Logger.LogFilePath);
        Logger.Log("Application started.");
    }
}

// Output:
// Static constructor executed.
// C:\Logs\logfile.txt
// Logging: Application started.
        

The Logger class has a static constructor that initializes the log file path when accessed for the first time.

Static Class vs. Non-Static Class

The table below compares static and non-static classes in C#.

When to Use Static Classes?

• For utility methods that do not require object instantiation (e.g., Math class).
• To store constants and configuration settings.
• For logging and debugging utilities.
• When all methods should be globally accessible without instantiation.