Re: Beginner on exception handling

Why does catch (A ex) rather than catch (B &ex) catch the B()
exception object? If I change the catch statement to catch (A &ex) it
doesn't catch B() anymore but catch (B &ex) does.
This might be quite a beginner question but you know, there's no
stupid questions just ....
Thanks Andreas

class A {
public:
    A () {
        std::cout << "A::A()" << std::endl;
    }
    virtual void Foo () {
        std::cout << "A::Foo()" << std::endl;
    }};

class B : public A {
public:
    B () {
        std::cout << "B::B()" << std::endl;
    }
    virtual void Foo () {
        std::cout << "B::Foo()" << std::endl;
    }};

int main(int argc, char** argv) {
    try {
        throw B();
    }
    catch ( A ex ) { //catch ( A &ex )
        ex.Foo ();
    }
    catch ( B& ex ) {
        ex.Foo ();
    }