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Groups > comp.lang.c++ > #12888
| From | "MikeWhy" <boat042-nospam@yahoo.com> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: noob question - destructors - freeing memory... |
| Date | 2011-12-30 20:06 -0600 |
| Organization | A noiseless patient Spider |
| Message-ID | <jdlqo9$i9j$1@dont-email.me> (permalink) |
| References | <jdlpc1$cdi$1@dont-email.me> |
someone wrote:
> Hi
>
> See this (stolen from the internet):
>
> ----------------------------------------
> #include <iostream>
> using namespace std;
>
> class Base
> {
> public:
> Base(){ cout<<"Constructing Base"<<endl;}
>
> // this is a destructor:
> virtual ~Base(){ cout<<"Destroying Base"<<endl;}
> };
>
> class Derive: public Base
> {
> public:
> Derive(){ cout<<"Constructing Derive"<<endl;}
> ~Derive(){ cout<<"Destroying Derive"<<endl;}
> };
>
> int main()
> {
> Base *basePtr = new Derive();
> // delete basePtr; // <<<======== !! ! ! ! ! NB !!
> return 0;
> }
>
> ----------------------------------------
>
> See middle line of main():
>
> delete basePtr; // <<<======== !! ! ! ! ! NB !!
>
>
> If I enable (uncomment) middle line, I get:
> Constructing Base
> Constructing Derive
> Destroying Derive
> Destroying Base
>
>
> If I disable (comment out) middle line, I get:
> Constructing Base
> Constructing Derive
>
>
> ========
>
> This, I didn't quite expect, because I thought that at the end of the
> program, all destructors where guaranteed to be called...
If pointers had destructors, what action should they take?
> In my case, I have a longer program and I allocate memory with one of
> my constructors, hence it is crucial to free the memory, but since the
> virtual destructor is never called, I never free the memory...
>
> In addition: In my full program (not shown here), I instantiate my new
> object like:
>
> int main(...)
> {
> ...
> Derive d1();
> return 0; // or exit(1); if something went wrong somewhere
> }
>
> Is it required that I do, like in the example above:
>
> int main(...)
> {
> ...
> Base *myPtr = new Derive();
foo(); // insert this line. See below.
> delete myPtr;
> return 0; // or exit(1); if something went wrong somewhere
> }
>
> ???????
Yes.
>
> But what if my code does an exit(1) somewhere, which it could do at
> least a dozens of times, in different parts of the program?
exit() is a function call. In your final example above, if foo() called
exit(1), will your destructor be called? Given what you saw earlier, how
does exit() trigger process termination?
If instead of calling exit(), foo() throws an uncaught exception. How does
the program behave?
Calling exit() is a very bad idea. Ditto for terminating threads, only more
so. A simple return will suffice. Find some other mechanism to trigger
process (and thread) termination.
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noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 02:43 +0100
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2011-12-30 20:06 -0600
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 03:33 +0100
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2011-12-30 21:22 -0600
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 04:57 +0100
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2011-12-30 22:28 -0600
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2011-12-30 22:43 -0600
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 05:49 +0100
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2011-12-30 23:56 -0600
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 07:07 +0100
Re: noob question - destructors - freeing memory... Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-12-31 01:50 -0800
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 18:13 +0100
Re: noob question - destructors - freeing memory... Nobody <nobody@nowhere.com> - 2012-01-01 08:37 +0000
Re: noob question - destructors - freeing memory... LR <lruss@superlink.net> - 2012-01-01 10:54 -0500
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 00:33 +0100
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2012-01-01 19:20 -0600
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 03:55 +0100
Re: noob question - destructors - freeing memory... Stefan Ensslen <stefan@zollsoft.de> - 2012-01-02 04:32 -0800
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 17:40 +0100
Re: noob question - destructors - freeing memory... Dombo <dombo@disposable.invalid> - 2012-01-02 19:14 +0100
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 21:30 +0100
Re: noob question - destructors - freeing memory... jgk@panix.com (Joe keane) - 2012-01-07 23:23 +0000
Re: noob question - destructors - freeing memory... "MikeWhy" <boat042-nospam@yahoo.com> - 2012-01-07 17:43 -0600
Re: noob question - destructors - freeing memory... Garrett Hartshaw <ghartshaw@gmail.com> - 2012-01-01 22:54 -0500
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 05:29 +0100
Re: noob question - destructors - freeing memory... Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-01 13:38 -0800
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 00:35 +0100
Re: noob question - destructors - freeing memory... "Bo Persson" <bop@gmb.dk> - 2011-12-31 12:55 +0100
Re: noob question - destructors - freeing memory... Garrett Hartshaw <ghartshaw@gmail.com> - 2011-12-30 22:50 -0500
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 05:37 +0100
Re: noob question - destructors - freeing memory... LR <lruss@superlink.net> - 2011-12-31 01:07 -0500
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 08:54 +0100
Re: noob question - destructors - freeing memory... Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-12-31 02:05 -0800
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 18:22 +0100
Re: noob question - destructors - freeing memory... Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-01 13:45 -0800
Re: noob question - destructors - freeing memory... Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-02 12:17 +0000
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 17:48 +0100
Re: noob question - destructors - freeing memory... Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-02 20:02 +0000
Re: noob question - destructors - freeing memory... Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-01 13:42 -0800
Re: noob question - destructors - freeing memory... Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-12-31 01:52 -0800
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 18:23 +0100
Re: noob question - destructors - freeing memory... Garrett Hartshaw <ghartshaw@gmail.com> - 2011-12-31 12:35 -0500
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 00:47 +0100
Re: noob question - destructors - freeing memory... Juha Nieminen <nospam@thanks.invalid> - 2011-12-31 09:40 +0000
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 18:26 +0100
Re: noob question - destructors - freeing memory... Garrett Hartshaw <ghartshaw@gmail.com> - 2011-12-31 13:00 -0500
Re: noob question - destructors - freeing memory... Nobody <nobody@nowhere.com> - 2012-01-01 08:57 +0000
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 00:43 +0100
Re: noob question - destructors - freeing memory... Juha Nieminen <nospam@thanks.invalid> - 2012-01-01 09:03 +0000
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 00:49 +0100
Re: noob question - destructors - freeing memory... LR <lruss@superlink.net> - 2012-01-01 21:11 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-02 05:23 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION
FOUND? Garrett Hartshaw <ghartshaw@gmail.com> - 2012-01-02 00:14 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-02 17:55 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-02 22:17 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION
FOUND? Garrett Hartshaw <ghartshaw@gmail.com> - 2012-01-02 16:40 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-03 00:48 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-02 14:47 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-03 00:43 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-02 20:30 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-03 19:08 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-03 17:46 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-04 21:11 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-04 18:56 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION
FOUND? Garrett Hartshaw <ghartshaw@gmail.com> - 2012-01-03 19:49 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-03 21:51 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION
FOUND? Garrett Hartshaw <ghartshaw@gmail.com> - 2012-01-03 23:37 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-04 14:24 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-04 21:20 +0100
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? LR <lruss@superlink.net> - 2012-01-04 18:51 -0500
Re: noob question - destructors - freeing memory... POSSIBLE SOLUTION FOUND? someone <newsboost@gmail.com> - 2012-01-05 07:32 +0100
Re: noob question - destructors - freeing memory... Garrett Hartshaw <ghartshaw@gmail.com> - 2012-01-01 23:02 -0500
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 05:33 +0100
Re: noob question - destructors - freeing memory... "io_x" <a@b.c.invalid> - 2012-01-02 11:05 +0100
Re: noob question - destructors - freeing memory... Juha Nieminen <nospam@thanks.invalid> - 2012-01-02 06:22 +0000
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2012-01-02 18:03 +0100
Re: noob question - destructors - freeing memory... "Bo Persson" <bop@gmb.dk> - 2011-12-31 12:51 +0100
Re: noob question - destructors - freeing memory... someone <newsboost@gmail.com> - 2011-12-31 18:18 +0100
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