What is the purpose of the static keyword in C++?

The keyword static in C++ has several meanings depending on the context:

1. Inside a function: a static local variable retains its value between function calls.

void func() {
    static int count = 0;
    count++;
    std::cout << count << std::endl;
}
// Each call to func() will increase count, and the value will not reset.

2. Inside a class: a static class member belongs to the class itself, not to any specific object. It is shared among all instances.

class MyClass {
public:
    static int staticVar;
};

int MyClass::staticVar = 0;
// Access: MyClass::staticVar

3. At the file level (global variables or functions): limits the scope of the variable or function to the current file (translation unit), preventing external linkage.

Thus, static manages the lifetime, scope, and ownership of data or functions.