BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Help with Error Message "EAccessViolation".          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Roberto Gomez Torres Guest Posted: Tue Apr 20, 2004 10:40 pm    Post subject: Help with Error Message "EAccessViolation". Hello List. Hope you can help me. I am using Borland C++ Builder 5.0 Pro with the Update Pack 1 installed. I have an application that was working just fine for a good time. Then I recompiled it and no errors or warnings were reported. But everytime I close the program (running from the IDE or as an EXE alone) I got the following errors: This one when running directly from Borland C++ Builder IDE and shows when I close the app : http://www.tiempo-digital.com/gallery/error.gif These others when running the EXE from the Windows Explorer : http://www.tiempo-digital.com/gallery/error1.gif http://www.tiempo-digital.com/gallery/error2.gif Have you seen something like this before ? Any hints on how to fix it ? Thanks a lot in advance. ====================== Roberto Gómez Torres Tiempo Digital Mexico City, Mexico www.tiempo-digital.com [email]roberto (AT) tiempo-digital (DOT) com[/email] ====================== Back to top KL Chin Guest Posted: Wed Apr 21, 2004 2:52 am    Post subject: Re: Help with Error Message "EAccessViolation". Hi Roberto, Look like one of your component/package have bugs in side, mean it did not check for NULL pointer. Regards KL Chin "Roberto Gomez Torres" <roberto (AT) tiempo-digital (DOT) com> wrote Quote: Hello List. Hope you can help me. I am using Borland C++ Builder 5.0 Pro with the Update Pack 1 installed. I have an application that was working just fine for a good time. Then I recompiled it and no errors or warnings were reported. But everytime I close the program (running from the IDE or as an EXE alone) I got the following errors: This one when running directly from Borland C++ Builder IDE and shows when I close the app : http://www.tiempo-digital.com/gallery/error.gif These others when running the EXE from the Windows Explorer : http://www.tiempo-digital.com/gallery/error1.gif http://www.tiempo-digital.com/gallery/error2.gif Have you seen something like this before ? Any hints on how to fix it ? Thanks a lot in advance. ====================== Roberto Gómez Torres Tiempo Digital Mexico City, Mexico www.tiempo-digital.com [email]roberto (AT) tiempo-digital (DOT) com[/email] ====================== Back to top JD Guest Posted: Wed Apr 21, 2004 9:01 am    Post subject: Re: Help with Error Message "EAccessViolation". "Roberto Gomez Torres" <roberto (AT) tiempo-digital (DOT) com> wrote: Quote: [...] But everytime I close the program (running from the IDE or as an EXE alone) I got the following errors: KL is correct in that a 3rd party component may be the cause but I doubt it. What kind of application is it? What does it do and how are you doing it? In a nut shell, 'undefined behavior' - a noun - occures when one violates the rules as defined by the standards. Once encountered, the program is unstable from that point on because the compiler is free (according to the standards) to deal with it any way that it wants - including formatting your hard drive. An Access Violation is generated by a program attempting to access invalid memory but not all attempts to access invalid memory generate an AV. That's because of the way that memory is managed by the VCL and the OS. A block a memory can be in a state of flux where your program sees it as free but it hasn't yet been released back to the OS. In this case, the OS doesn't complain if you access it but according to the standards, the program has just encountered undefined behavior. In my experiance, the behavior you described: that it only showed up after a recompile; has always lead back to poor memory management. Tracking down this problem is not going to be difficult but it's a PITA because it's tediouse work. The first thing that you should do is to assign NULL to all pointers as they are defined: char* Buffer = NULL; If the pointer is defined as global, assign NULL to it in the constructor: __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) { Buffer = NULL; } Then test all pointers before you access them: if( Buffer ) Buffer[ 99 ] = '?'; else throw( "Buffer was invalid" ); You also need to make sure that you don't access pointers after they have been deleted. If you set them to NULL after deletion: delete [] Buffer; Buffer = NULL; the intergrity of testing the pointer before it's accessed is maintained. It also takes care of another potential problem of deleting a pointer twice. This works because it legal to delete a NULL pointer. While it doesn't reveal the err of your ways, it serves the compiler well. However, being consistant with tracking down the offending line(s) of code, change the delete to: if( Buffer ) delete [] Buffer; else throw( "Invalid deletion of Buffer" ); Buffer = NULL; Then you need to match up all of your 'new'(s) with 'delete'(s) and 'new[]'(s) with 'delete[]'(s): TStringList* pList = new TStringList; .... delete pList; char* Buffer = new char[ 100 ]; .... delete [] Buffer; and make sure that you aren't accessing beyond the pointers allocated block: char c = Buffer[ 100 ]; is undefined behavior and *might* cause and AV where as: Buffer[ 100 ] = '?'; is destructive and worse than the first. Remember that once your program encounters undefined behavior, all bets are off. Keep in mind that just because are particulare compile doesn't break, it doesn't mean that the program isn't still broken - as demonstrated by your experiance where it was working but now isn't. Once you start, to be sure that you've cleared the problem, you need to complete the entire process because it's possible that there is more than one problem. ~ JD Back to top Roberto Gomez Torres Guest Posted: Wed Apr 21, 2004 6:01 pm    Post subject: Re: Help with Error Message "EAccessViolation". KL, JD, Thank you so much for the help and pointers. This problem is strange since I did not change a single line of code. Yesterday I recompiled the same project on a Windows ME machine, with all the same Borland C++ Builder Environment. And the problem when I close the program is not there !!! Will look in detail today on the Windows 2000 Pro Machine. Thanks a lot guys. ====================== Roberto Gómez Torres Tiempo Digital Mexico City, Mexico www.tiempo-digital.com [email]roberto (AT) tiempo-digital (DOT) com[/email] ====================== Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  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.