Re: [Dev-C++] Constructor and Destructor

[Per W. <pw...@ia...>]

Nothing strange here... c->f() only works because:

1: A::f is not virtual, i.e. there is no need to lookup a function pointer
indirectly through the object. It is just a normal function call.

2: A::f() does not try to reference any dynamic data owned by the object.
In this case it calls a globally declared stream with a constant text
string. If it had tried to call a virtual method, or update any member
variables of the A class, it would have failed.

/Per W

On Wed, 9 Jul 2003, Avik Ghose wrote:

>
> Hi Lohit,
>
> look for my answers inline pls.
>
> "Verma, Lohit" <Loh...@hp...> wrote:
>
> Hi
> I have a question regarding constructors and destructors, and about class pointers
> If I have a class A (see below), Now the second call crashes
>
> Also I can call a member function without allocating memory for a class object.
>
> Please see code below and advice.
>
> Thanks a lot
>
> Lohit
>
>
>
> #include <iostream>
> using namespace std;
>
> class A{
>
> public:
> A(){
> delete this;
> }
> ~A(){
> cout<<"~A";
> }
>
> f(){
>
> cout<<"HELLO\n";
>
> }
>
> };
>
> int main()
> {
>     A *a=new A();//works
>
> It works because you have alloated the object a from heap and the 'delete' operator works correctly in this case.
>
>
>     A b;//crashes why?? how is it any different from above.
>
> This crashes beacuse a is allocated from stack or compile time memory, so any attempt to explicitly delete it will result in a crash.
>
>         A *c;
>
>                 c->f();//works why when I have not allocated any memory for this.
>
> The third part got me stumped!!! I am attaching a code, the results are strange on devcpp!
>
> }
>
>
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>
>
>
> Thanx and Regards
>    Avik Ghose
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