His c++ syntax is just fine, his obj can be understood as a pointer to an object:

#include <iostream.h>

class aclass {
    public:
        int first_perfect_number(void); 
};

int aclass::first_perfect_number(void) {
    return 6;
}

int main() {
    aclass * ap = new aclass();
    cout << "first perfect number is: " << ap->first_perfect_number() 
+<< endl;
}
[download]