Static classes

Learn how to define and use static classes.

Static classes

A static class cannot be instantiated and may contain only static members. It is declared as static class Config { ... }.

Static classes are ideal for collecting helper and utility functions: Math, Convert, Console are examples. Because no instance can be created, new Config() is a compile error. Members must also be marked static.

When to use a static class?

If every member of a class is already static, marking the class itself static is recommended. It prevents accidental instantiation and signals intent.

For example, a StringHelper class that only has static methods like Capitalize and Truncate is a good candidate. If you need to hold instance state, a static class is wrong; use a normal class.

Exercise Configuration class

Define a static class Config. Add a public static string AppName = "Quiz"; field. In Main, print Config.AppName.

Show example solution

Add `static class Config { public static string AppName = "Quiz"; }`. In Main write `Console.WriteLine(Config.AppName);`.
Example solution:
using System;

static class Config
{
    public static string AppName = "Quiz";
}

class Program
{
    static void Main()
    {
        Console.WriteLine(Config.AppName);
    }
}

Test yourself

Match: static class properties

static class

cannot be instantiated
new Config()

compile error
member

must be static
use case

helper functions

Fill in the blank: static class declaration

static ____
{
    public static string AppName = "Quiz";
}

Show answer

static class Config
{
    public static string AppName = "Quiz";
}

Which statement about static classes is FALSE?
- A static class cannot be instantiated.
- All members of a static class must be static.
- Math is a static class.
- A static class can have an instance constructor.
Show answer

A static class can have an instance constructor. — Correct (false statement). A static class cannot have an instance constructor; only a static constructor is allowed.

Next lesson: const and readonly

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