Summary - Static members

C# course · Intermediate · Lesson 35/116

Combine static class, methods and readonly to write a Configuration helper.

Summary - Static members

In this group you learned static members: a static field is shared across all instances, a static method is called via the class name, a static class cannot be instantiated. const holds a compile-time constant, readonly a runtime immutable value. A static constructor runs once when the class loads.

Static members suit helper operations that don't depend on instance state, shared counters and immutable values. If you need instance state, use a normal class instead.

Exercise Counter class (summary)

Add a public static int Count = 0; field to Counter. The Increment static method does Count++. In Main, call Counter.Increment() twice and print Counter.Count.

Show example solution

Add `public static int Count = 0;` to Counter. In Increment write `Count++;`. In Main write `Counter.Increment(); Counter.Increment(); Console.WriteLine(Counter.Count);`.
Example solution:
using System;

class Counter
{
    public static int Count = 0;

    public static void Increment()
    {
        Count++;
    }
}

class Program
{
    static void Main()
    {
        Counter.Increment();
        Counter.Increment();
        Console.WriteLine(Counter.Count);
    }
}

Exercise Helper class (summary)

Define a static class Helper. Add a public static int Add(int a, int b) method whose body is return a + b;. In Main, call Helper.Add(3, 4) and print the result.

Show example solution

Add `static class Helper { public static int Add(int a, int b) { return a + b; } }`. In Main write `Console.WriteLine(Helper.Add(3, 4));`.
Example solution:
using System;

static class Helper
{
    public static int Add(int a, int b)
    {
        return a + b;
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(Helper.Add(3, 4));
    }
}

Next step

Static members simplify many real cases: singleton patterns, extension methods and helper libraries. The next group dives deeper into constants with const, readonly, static readonly and enum.

Remember: static members can hurt testability; don't overuse them. Prefer a normal class when you need instance state.

Test yourself

Which statement about static members is correct?
- A static class cannot be instantiated.
- A static method can access instance fields.
- A static field holds a separate copy per instance.
- A static constructor runs on every instance creation.
Show answer

A static class cannot be instantiated. — Correct. A static class cannot be instantiated; all members must be static.

Fill in the blank: static method

class Helper
{
    public static int Add(int a, int b)
    {
        return ____;
    }
}

Show answer

class Helper
{
    public static int Add(int a, int b)
    {
        return a + b;
    }
}

Summary - Static members