What are the functions and characteristics of a static class in C++?

A static class is a special type of class that only contains static member variables and static member functions, without any non-static members. The purpose and characteristics of a static class are as follows:

Function:

1. Encapsulate a set of related static data and static methods to easily organize and manage code.
2. To avoid creating instances of objects, simply access static members directly through the class name.
3. Can be used for implementing singleton patterns, utility classes, and other scenarios.

Characteristics:

1. Static classes cannot be instantiated, and they cannot contain non-static member variables and member functions.
2. Static member variables are initialized when the program starts and exist throughout the entire runtime of the program.
3. Static member functions can be called directly by using the class name without the need to create an object.
4. Static class member functions can only access static member variables and other static member functions, not non-static members.
5. Static classes cannot inherit from other classes, nor can they be inherited by other classes.

In general, static classes are mainly used to encapsulate public static data and methods to improve the organization and maintainability of code.