BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Using TFileStream to Save a Structure Containing an Array          BorlandTalk.com Forum Index -> C++ Builder (Language C++) View previous topic :: View next topic   Author Message Del Ventruella Guest Posted: Wed Jun 15, 2005 12:48 pm    Post subject: Using TFileStream to Save a Structure Containing an Array How does one use TFileStream in Borland Builder 6.0 to save and then recall a structure FILE containing an array? For Example, how would I save and then recall "ArraysOfNums" below?: Struct ArraysOfNums { double A[28]; double B[28]; }; Thanks in advance to whomever might take a moment to clear this up for me. Sincerely, Del Ventruella Back to top Liz Albin Guest Posted: Wed Jun 15, 2005 2:15 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra On 15 Jun 2005 05:48:52 -0700, Del Ventruella wrote: Quote: Struct ArraysOfNums { double A[28]; double B[28]; }; for one thing, it would be struct, not Struct Check the ReadBuffer() and WriteBuffer() methods, in ether case, Count will be something like int Count = sizeof(ArrayOfNums); -- Good luck, liz Back to top Del Ventruella Guest Posted: Wed Jun 15, 2005 2:59 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra "Del Ventruella" <ventruella (AT) hotmail (DOT) com> wrote: Quote: How does one use TFileStream in Borland Builder 6.0 to save and then recall a structure FILE containing an array? For Example, how would I save and then recall "ArraysOfNums" below?: Struct ArraysOfNums { double A[28]; double B[28]; }; Thanks in advance to whomever might take a moment to clear this up for me. Sincerely, Del Ventruella I have tried the following using the ReadBuffer and WriteBuffer methods, but with not success in saving the structures of arrays of doubles: TStream* stream1=new TFileStream(NameOfFile, fmCreate | fmShareDenyNone); stream1->WriteBuffer((char*)(&*ArrayOfNums), sizeof(ArrayOfNums)); AND TStream* stream1=new TFileStream(filename, fmOpenRead | fmShareDenyNone); stream1->ReadBuffer((char*)(&*ArrayOfNums), sizeof(ArrayOfNums)); I am trying to cast the address of the first element of the structure (ArrayOfNums) as a char pointer and get the code to read (or write) to the end of the structure based upon the size of the structure. There may be a much easier approach employing a more straightforward application of a buffer, but translating a structure containing arrays of doubles such as ArrayOfNums into a buffer seems to require a bit more than doing the same for an AnsiString. I am blanking right now in that regard. Thanks for any effort to point me in the right direction. Sincerely, Del Ventruella Back to top Liz Albin Guest Posted: Wed Jun 15, 2005 3:04 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra On 15 Jun 2005 07:59:44 -0700, Del Ventruella wrote: Quote: stream1->WriteBuffer((char*)(&*ArrayOfNums), sizeof(ArrayOfNums)); please give your exact code and say exactly what errors you're gotten. -- Good luck, liz Back to top Alan Bellingham Guest Posted: Wed Jun 15, 2005 3:51 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra "Del Ventruella" <ventruella (AT) hotmail (DOT) com> wrote: Quote: For Example, how would I save and then recall "ArraysOfNums" below?: Struct ArraysOfNums { double A[28]; double B[28]; }; I have tried the following using the ReadBuffer and WriteBuffer methods, but with not success in saving the structures of arrays of doubles: (Please consider keeping your line length below the 80 mark.) Quote: stream1->WriteBuffer((char*)(&*ArrayOfNums), sizeof(ArrayOfNums)); Err, you expect this to work? ArraysOfNums is a _type_ - in other words, there may be any one of a number of them on the system. They'll all be the same size (which means that your sizeof() will work), but how is the code to guess which instance (if any) to save? You need to declare an actual instance first: ArrayOfNums MyArray; // ... and then you will pass the address of the instance: stream1->WriteBuffer(&MyArray, sizeof MyArray); BTW - your cast to char* was completely unnecessary, and though not actually dangerous, inadvisable, since the WriteBuffer method actually takes a 'void const *'. I'll leave the read logic to you, since it's almost identical. Alan Bellingham -- ACCU Conference 2006 - 19-22 April, Randolph Hotel, Oxford, UK Back to top Del Ventruella Guest Posted: Wed Jun 15, 2005 4:03 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra Alan Bellingham <alanb (AT) episys (DOT) com> wrote: Quote: "Del Ventruella" <ventruella (AT) hotmail (DOT) com> wrote: For Example, how would I save and then recall "ArraysOfNums" below?: Struct ArraysOfNums { double A[28]; double B[28]; }; I have tried the following using the ReadBuffer and WriteBuffer methods, but with not success in saving the structures of arrays of doubles: (Please consider keeping your line length below the 80 mark.) stream1->WriteBuffer((char*)(&*ArrayOfNums), sizeof(ArrayOfNums)); Err, you expect this to work? ArraysOfNums is a _type_ - in other words, there may be any one of a number of them on the system. They'll all be the same size (which means that your sizeof() will work), but how is the code to guess which instance (if any) to save? You need to declare an actual instance first: ArrayOfNums MyArray; // ... and then you will pass the address of the instance: stream1->WriteBuffer(&MyArray, sizeof MyArray); BTW - your cast to char* was completely unnecessary, and though not actually dangerous, inadvisable, since the WriteBuffer method actually takes a 'void const *'. I'll leave the read logic to you, since it's almost identical. Alan Bellingham -- ACCU Conference 2006 - 19-22 April, Randolph Hotel, Oxford, UK I'll try again. (I left the creation of the instance of the structure out of the prior post, but it is in my code.) Most importantly, Thank you. Sincerely, Del Ventruella Back to top Liz Albin Guest Posted: Wed Jun 15, 2005 4:39 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra On 15 Jun 2005 09:03:30 -0700, Del Ventruella wrote: Quote: I'll try again. (I left the creation of the instance of the structure out of the prior post, but it is in my code.) Most importantly, Thank you. Please wrap your lines. The reason I asked for exact code was that it was completely unclear whether ArrayOfNum was a type or an instance. So, please show the code that doesn't work, and explain precisely /what/ doesn't work. -- Good luck, liz Back to top Sergiy Kanilo Guest Posted: Wed Jun 15, 2005 7:11 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra "Alan Bellingham" <alanb (AT) episys (DOT) com> wrote Quote: "Del Ventruella" <ventruella (AT) hotmail (DOT) com> wrote: For Example, how would I save and then recall "ArraysOfNums" below?: Struct ArraysOfNums { double A[28]; double B[28]; }; I have tried the following using the ReadBuffer and WriteBuffer methods, but with not success in saving the structures of arrays of doubles: (Please consider keeping your line length below the 80 mark.) stream1->WriteBuffer((char*)(&*ArrayOfNums), sizeof(ArrayOfNums)); Err, you expect this to work? ArraysOfNums is a _type_ - in other words, ArraysOfNums is a type, ArrayOfNums could be anything My gues is that ArrayOfNums probably _a pointer_ to ArraysOfNums and problem with saving is that sizeof of pointer is not correct size of the saved data Cheers, Serge Back to top Alan Bellingham Guest Posted: Thu Jun 16, 2005 12:49 am    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra "Sergiy Kanilo" <skanilo (AT) artannlabs (DOT) com> wrote: Quote: ArraysOfNums is a type, ArrayOfNums could be anything Ah, not obvious. In fact, if the OP was trying to hide what was going on, that would be a good way to do it. Quote: My gues is that ArrayOfNums probably _a pointer_ to ArraysOfNums and problem with saving is that sizeof of pointer is not correct size of the saved data It depends. Is it a compilation error, or a runtime error? Alan Bellingham -- Me <url:mailto:alanb (AT) episys (DOT) com> <url:http://www.doughnut.demon.co.uk/> ACCU - C, C++ and Java programming <url:http://accu.org/> The 2004 Discworld Convention <url:http://dwcon.org/> Back to top Sergiy Kanilo Guest Posted: Thu Jun 16, 2005 1:14 am    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra "Alan Bellingham" <alanb (AT) episys (DOT) com> wrote Quote: "Sergiy Kanilo" <skanilo (AT) artannlabs (DOT) com> wrote: ArraysOfNums is a type, ArrayOfNums could be anything Ah, not obvious. In fact, if the OP was trying to hide what was going on, that would be a good way to do it. My gues is that ArrayOfNums probably _a pointer_ to ArraysOfNums and problem with saving is that sizeof of pointer is not correct size of the saved data It depends. Is it a compilation error, or a runtime error? Probably there is no error, otherwise OP mentioned it. Insted he said "I have tried the following ... but with not success in saving the structures of ...". If ArrayOfNums is a pointer, that is exactly what should happen. Could be that in previous version of the code, ArrayOfNums was an automatic or static array of structures (sizeof(ArrayOfNums) gave correct size), but later the array was replaced with a pointer and memory allocation, and code failed in saving the data. Of course, it is just speculation, but I believe it is a very common situation. Cheers, Serge Back to top Alan Bellingham Guest Posted: Thu Jun 16, 2005 8:54 am    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra "Sergiy Kanilo" <skanilo (AT) artannlabs (DOT) com> wrote: Quote: It depends. Is it a compilation error, or a runtime error? Probably there is no error, otherwise OP mentioned it. Insted he said "I have tried the following ... but with not success in saving the structures of ...". Hmm, and I thought he meant that he couldn't work out how to get it to compile. (The 'with not success' I interpreted to be an error at compilation stage, since what was provided was apparently uncompilable.) Alan Bellingham -- Me <url:mailto:alanb (AT) episys (DOT) com> <url:http://www.doughnut.demon.co.uk/> ACCU - C, C++ and Java programming <url:http://accu.org/> The 2004 Discworld Convention <url:http://dwcon.org/> Back to top Liz Albin Guest Posted: Thu Jun 16, 2005 1:00 pm    Post subject: Re: Using TFileStream to Save a Structure Containing an Arra On Thu, 16 Jun 2005 09:54:59 +0100, Alan Bellingham wrote: Quote: Hmm, and I thought he meant that he couldn't work out how to get it to compile. (The 'with not success' I interpreted to be an error at compilation stage, since what was provided was apparently uncompilable.) Same here -- starting with the Struct declaration -- which is also why I was completely unsure whether he was using a type or an instance -- Good luck, liz 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 (Language C++) 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.