C# – Nested Types

Nested Types

• Nested type is declared within the scope of another type.
• It can access the enclosing type’s private members and everything else the enclosing type can access.
• It can be declared with the full range of access modifiers, rather than just public and internal.
• The default accessibility for a nested type is private rather than internal.
• Accessing a nested type from outside the enclosing type requires qualification with the enclosing type’s name (like when accessing static members).
• All types (classes, structs, interfaces, delegates and enums) can be nested inside
  either a class or a struct.

public class TopLevel
{
	public class Nested { }               // Nested class
	public enum Color { Red, Blue, Tan }  // Nested enum
}

static void Main()
{
	TopLevel.Color color = TopLevel.Color.Red;	
}

//Private member visibility
public class TopLevel
{
	static int x;
	public class Nested
	{
		public static void Foo() { Console.WriteLine (TopLevel.x); }
	}
}

static void Main()
{
	TopLevel.Nested.Foo();
}

//Protected member visibility
public class TopLevel
{
	protected class Nested { }
}

public class SubTopLevel : TopLevel
{
	static void Foo() { new TopLevel.Nested(); }
}

static void Main()
{
}