What is the difference in the use of the keyword static in C and C++ languages?

In the C language, the keyword static is used to modify the scope and lifetime of variables and functions:

• For global variables and functions, static limits their scope to the current file (internal linkage), meaning they are not visible from other files.
• For local variables within a function, static preserves the variable's value between function calls (the variable lives for the duration of the program).

In C++, static retains these meanings but also adds usage in the context of classes:

• In a class, static variables and methods belong to the class itself rather than to any specific object. Such members exist as a single instance for the entire class.

Example:

// C and C++
static int counter = 0; // visible only in this file

void func() {
    static int callCount = 0; // preserves value between calls
    callCount++;
}

// In C++
class MyClass {
public:
    static int staticValue; // shared among all objects
    static void staticMethod() {
        // ...
    }
};

int MyClass::staticValue = 0;

Thus, the main difference is that in C++, static is also used to define static class members, which is not present in C.