The purpose of the static keyword in C++

In C++, the static keyword can be used for several different purposes:

1. Using the “static” keyword inside a function to modify a local variable causes the variable to persist throughout the entire duration of the program instead of just during the execution of the function. This means that the value of the variable is retained each time the function is called, rather than being reset each time.
2. Using static to modify a global variable outside of a function limits the scope of the variable to the file in which it is declared, preventing other files from accessing it and avoiding naming conflicts between different files.
3. When a member variable of a class is marked with the “static” keyword, it is called a static member variable. This variable belongs to the entire class rather than a specific instance of the class. Static member variables are shared among all instances of the class and can be accessed directly by the class name.
4. When using the static modifier to decorate a member function within a class, the function is known as a static member function. It does not belong to a specific instance of the class, but rather to the class itself. Static member functions can be called directly using the class name, without needing to create an instance of the class.

In general, the static keyword can be used to modify variables and functions, altering their scope, lifespan, or access methods.