Can Static Member Methods Be Called on Class Instances in C ?

Calling Static Member Methods on Class Instances in C

The question arises regarding the validity of calling static member methods on class instances in C . Static member methods are typically invoked through the class name, but the code snippet below seems to contradict this convention:

class Test {
public:
    static void DoCrash() { std::cout << "TEST IT!" << std::endl; }
};

int main() {
    Test k;
    k.DoCrash();
}

Question:

• Is it correct to call a static member method using class instance syntax?
• If so, what is the rationale behind it?

Answer:

While static member methods conventionally are called through the class name, the C standard allows them to be invoked on class instances. This is evident from the following section in the C 03 standard:

"A static member s of class X may be referred to using the qualified-id expression X::s; it is not necessary to use the class member access syntax (5.2.5) to refer to a static member. A static member may be referred to using the class member access syntax, in which case the object-expression is evaluated."

This means that calling a static member method via class instance syntax is not just allowed but also has a different semantic. In such cases, the object-expression is evaluated, which potentially offers benefits in the context of generic programming.

Example:

The following code demonstrates how static member methods can be used with both class name and instance syntax:

class Process {
public:
    static void Reschedule() { /* ... */ }
};

int main() {
    Process::Reschedule();  // Using class name syntax
    Process p;
    p.Reschedule();         // Using instance syntax
}

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