C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Function / Method in class          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Riaan Guest Posted: Mon Jan 30, 2006 10:00 am    Post subject: Function / Method in class Hi Everybody, I created my own class with 2 methods (both public) in it. When I use the 1 method it works fine, as soon as I make a call to the other method, the program crashes. I removed all code from the second method already, also removed all variables passed to it.. what can it be ?? -- Riaan Bekker Back to top Stephan Brönnimann Guest Posted: Mon Jan 30, 2006 10:00 am    Post subject: Re: Function / Method in class Riaan wrote: Quote: Hi Everybody, I created my own class with 2 methods (both public) in it. When I use the 1 method it works fine, as soon as I make a call to the other method, the program crashes. I removed all code from the second method already, also removed all variables passed to it.. what can it be ?? -- Riaan Bekker You should post a minium compileable code sample, see http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.8. My best guess: you've used different versions of the class' header file. Stephan Back to top Bob Hairgrove Guest Posted: Mon Jan 30, 2006 10:00 am    Post subject: Re: Function / Method in class On Mon, 30 Jan 2006 11:14:04 +0200, "Riaan" <riaan@c-pos.co.za> wrote: Quote: Hi Everybody, I created my own class with 2 methods (both public) in it. When I use the 1 method it works fine, as soon as I make a call to the other method, the program crashes. I removed all code from the second method already, also removed all variables passed to it.. what can it be ?? Show us the code. -- Bob Hairgrove NoSpamPlease (AT) Home (DOT) com Back to top Riaan Guest Posted: Mon Jan 30, 2006 11:00 am    Post subject: Re: Function / Method in class Hi Stephan, thanks man, you gave me an idea and I had a look at the created DLL.. it was a different version !! THANKS MAN -- Riaan Bekker Odyssey Software "Stephan Brönnimann" <broeni (AT) hotmail (DOT) com> wrote in message news:1138614337.399970.21120 (AT) g14g2000cwa (DOT) googlegroups.com... Quote: Riaan wrote: Hi Everybody, I created my own class with 2 methods (both public) in it. When I use the 1 method it works fine, as soon as I make a call to the other method, the program crashes. I removed all code from the second method already, also removed all variables passed to it.. what can it be ?? -- Riaan Bekker You should post a minium compileable code sample, see http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.8. My best guess: you've used different versions of the class' header file. Stephan Back to top Bob Hairgrove Guest Posted: Mon Jan 30, 2006 1:00 pm    Post subject: Re: Function / Method in class On Mon, 30 Jan 2006 12:04:11 +0200, "Riaan" <riaan@c-pos.co.za> wrote: Quote: Here is the code ! The functions I am talking about is LogEvent (not working) and ShowEvents( working ) OK, I see that you seem to have gotten it to work...however, some comments are in order: (1) You need a virtual destructor in EventsInterface if you are ever going to delete a derived class through a pointer to EventsInterface. (2) In this code, you should remove the unnecessary semicolons after inline definitions, e.g.: Quote: //************ //Login Plugin class LoginInterface { public: virtual ~LoginInterface() {}; // ^ no semicolon here virtual void ShowLogin(void) const = 0; // ^ semicolon is necessary }; (3) I believe you must also provide an empty definition for the destructor here in addition to making it pure virtual: Quote: //*************** //Database Plugin class ConnInterface { public: virtual ~ConnInterface() = 0; }; // e.g., somewhere outside of the above declaration: ConnInterface::~ConnInterface() {} (4) Here's a serious bug: It seems that Events::fileControl doesn't get initialized until Events::LoadPlugins is called. But if "plugin" isn't properly initialized (line 197 in the function's body), fileControl is also not initialized. However, the destructor of Events deletes fileControl. You need to initialize fileControl to 0 in your constructor, also in case an exception occurs. Since you have more than one pointer member in the class, it would also be a good idea to use smart pointers instead of plain pointers -- this is especially important WRT exception safety. (5) There is no exception handling anywhere. Have you thought about this at all yet? Since I haven't ever done any Qt development, I obviously cannot hope to compile the code, so I didn't look at the rest. -- Bob Hairgrove NoSpamPlease (AT) Home (DOT) com Back to top Riaan Guest Posted: Tue Jan 31, 2006 8:00 am    Post subject: Re: Function / Method in class Hi Bob, I would like to know what do you mean by using SMART pointers instead of normal pointers ? -- Riaan Bekker Back to top Riaan Guest Posted: Tue Jan 31, 2006 8:00 am    Post subject: Re: Function / Method in class Hi Bob, Thank you very much for the comments, I do appreciate it much. Would you please give me an example of the kind of exception handling that I can add to the program ? Regards, -- Riaan Bekker Back to top Riaan Guest Posted: Tue Jan 31, 2006 8:00 am    Post subject: Re: Function / Method in class Bob, As soon as I set my fileControl to 0 in my class constructor the program already gives an exception error. fileControl = 0; In what other way can I init the fileControl plug-in ? Back to top Bob Hairgrove Guest Posted: Tue Jan 31, 2006 10:00 am    Post subject: Re: Function / Method in class On Tue, 31 Jan 2006 09:22:56 +0200, "Riaan" <riaan@c-pos.co.za> wrote: Quote: Hi Bob, Thank you very much for the comments, I do appreciate it much. Would you please give me an example of the kind of exception handling that I can add to the program ? Regards, http://www.parashift.com/c++-faq-lite/exceptions.html -- Bob Hairgrove NoSpamPlease (AT) Home (DOT) com Back to top Bob Hairgrove Guest Posted: Tue Jan 31, 2006 11:00 am    Post subject: Re: Function / Method in class On Tue, 31 Jan 2006 09:23:56 +0200, "Riaan" <riaan@c-pos.co.za> wrote: Quote: Hi Bob, I would like to know what do you mean by using SMART pointers instead of normal pointers ? http://www.parashift.com/c++-faq-lite/freestore-mgmt.html -- Bob Hairgrove NoSpamPlease (AT) Home (DOT) com Back to top Bob Hairgrove Guest Posted: Tue Jan 31, 2006 11:00 am    Post subject: Re: Function / Method in class On Tue, 31 Jan 2006 09:43:36 +0200, "Riaan" <riaan@c-pos.co.za> wrote: Quote: Bob, As soon as I set my fileControl to 0 in my class constructor the program already gives an exception error. fileControl = 0; In what other way can I init the fileControl plug-in ? Have you tried this? Events::Events() : fileControl(0) { // etc. }; -- Bob Hairgrove NoSpamPlease (AT) Home (DOT) com Back to top Riaan Guest Posted: Wed Feb 01, 2006 5:13 pm    Post subject: Re: Function / Method in class Bob, I tried Events::Events() : fileControl(0) but it still crashes on the first use of the fileControl (obviously, because the object is not created). If I want to create an exception handler in my constructor, to check if the fileControl object was created, how will I halt the usage of the Event class. Without the fileControl object the event class can not continue with its functionality Regards -- Riaan Bekker Back to top Bob Hairgrove Guest Posted: Sat Feb 04, 2006 12:00 pm    Post subject: Re: Function / Method in class On Wed, 1 Feb 2006 14:13:53 +0200, "Riaan" <riaan@c-pos.co.za> wrote: Quote: Bob, I tried Events::Events() : fileControl(0) but it still crashes on the first use of the fileControl (obviously, because the object is not created). If I want to create an exception handler in my constructor, to check if the fileControl object was created, how will I halt the usage of the Event class. Without the fileControl object the event class can not continue with its functionality But you didn't create fileControl in your constructor ... you did it later in a separate function (forgot which one)?? If you initialize the pointer to 0 as I showed you (i.e. in the constructor's initialization list), then call some other function from the body of the constructor to set its value, you can check it after the function returns to see if it is still zero. If it is still 0, then I would throw an exception from the constructor's body which will cause the creation of that particular instance of Events to fail. Otherwise, you risk having a fully-created object which has no fileControl which could be used by mistake. Check out the FAQ on exceptions and exception handling ... just use the links I gave you previously and search for it. -- Bob Hairgrove NoSpamPlease (AT) Home (DOT) com Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.