C++ Static Members: Shared Variables and Functions of a Class

This article introduces the concepts, usage, and precautions of static members (variables and functions) in C++. Static members address the issue that ordinary member variables cannot share data: Static member variables (modified by `static`) belong to the entire class, are stored in the global data area, and are shared by all objects. They require initialization outside the class (e.g., `int Student::count = 0;`) and can be accessed via the class name or an object (e.g., `Student::count`). In the example, the `Student` class uses the static variable `studentCount` to count the number of objects, incrementing it during construction and decrementing it during destruction to demonstrate the sharing feature. Static member functions are also modified by `static`, belong to the class rather than objects, and have no `this` pointer. They can only access static members and can be called via the class name or an object (e.g., `Student::getCount()`). Precautions: Static member variables must be initialized outside the class; static functions cannot directly access non-static members; avoid excessive use of static members to reduce coupling. Summary: Static members implement class-shared data and utility functions, enhancing data consistency and are suitable for global states (e.g., counters). However, their usage scenarios should be reasonably controlled.