What is a nested class and Why can it be useful

What is a nested class? Why can it be useful?

Answer:

A nested class is a class enclosed within the scope of another class.

For example: //

Example 1:Nested class

class OuterClass {

class NestedClass { // ... };

// ... };

Nested classes are useful for organizing code and controlling access and dependencies. Nested classes obey access rules just like other parts of a class do; so, in Example 1, if NestedClass is public then any code can name it as OuterClass::NestedClass. Often nested classes contain private implementation details, and are therefore made private; in Example 1, if NestedClass is private, then only OuterClass's members and friends can use NestedClass. When you instantiate as outer class, it won't instantiate inside class.