This

[parksie]

Hmm bizarre thing there

Anyway, this is a pointer to the instance of that class. What you're doing with the second one is you're passing a pointer rather than a class, so it shouldn't even compile

#include <iostream>

using namespace std; // Just making you standards-compliant :)

class CDummy {
public:
    int isitme(CDummy *param); // Using pointers instead, it's easier
};

int CDummy::isitme(CDummy *param) {
    if(param == this) return 1;
    return 0;
}

int main() {
    CDummy a;
    CDummy *b = &a;

    if(b->isitme(&a))
        cout <<"yep, &a is b\n";
    else
        cout << "nope, don't know this one\n";

    return 0;
}

That should print "yep, &a is b"