Static Data member initialization?

While initializing a static data member we write:-

int Student::noOfStudents;

Here we are specifying the return type as 'int'; but this is not a function; why there is need to specify return type; similarly we have not defined the return type in prototype or once we declared static data member inside the body of the class; kindly clarify?

class Student{

private:

static int noOfStudents;

public:

  …

};

int Student::noOfStudents = 0;

or

int Student::noOfStudents;


Both initializations result in same value that is 0. Return type is important as without that coder won't know what to store.