Question

Is it possible to invoke a c++ class method without first creating a class instance?

Suppose we have the following code:

// just an example 
#include <iostream>
using namespace std;

class MyClass {
    public:
        MyClass();
        ~MyClass();
        int MyMethod(int *a, int *b);
};

// just a dummy method
int MyClass::MyMethod(int *a, int *b){;
    return a[0] - b[0];
}

---

Here’s another example:

#include <iostream>
using namespace std;

class MyClassAnother {
    public:
        MyClassAnother();
        ~MyClassAnother();
        int MyMethod(int *a, int *b);
};

// just a dummy method
int MyClassAnother::MyMethod(int *a, int *b){;
    return a[0] + b[0];
}

As we can see, in the above examples, both classes have no internal variables and use dummy constructors / destructors; Their sole purpose is to expose one public method, MyMethod(..). Here’s my question: assume there are 100 such classes in the file (all with different class names, but with an identical structure — one public method having the same prototype — MyMethod(..).

Is there a way to invoke the MyMethod(..) method calls of each one of the classes without first creating a class instance for each?

Answer 1

Use the keyword ‘static’ to declare the method:

static int MyMethod( int * a, int * b );

Then you can call the method without an instance like so:

int one = 1;
int two = 2;

MyClass::MyMethod( &two, &one );

‘static’ methods are functions which only use the class as a namespace, and do not require an instance.