BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  FILE Problem          BorlandTalk.com Forum Index -> C++ Builder (Native API) View previous topic :: View next topic   Author Message Marco mliorniNoMail.com Guest Posted: Mon Mar 07, 2005 10:09 am    Post subject: FILE Problem Hi everyone, i use "File *My_file" to create, save and read file in my applycation but sometimes it doesn't work and i can't understand why. Is there some Win-XP settings that could give problems? Thanks in advanced. Marco Back to top Andrue Cope [TeamB] Guest Posted: Mon Mar 07, 2005 10:27 am    Post subject: Re: FILE Problem "Marco" mliorni"NoMail.com wrote: Quote: i use "File *My_file" to create, save and read file in my applycation but sometimes it doesn't work and i can't understand why. What do you mean by that? This is the newsgroup section for questions relating to the Windows API and that means using CreateFile() to create a file. If it were the .language section than "FILE *" would be meaningful but "File *My_file" isn't. I suggest you post a short, preferably compilable example. Remember that to get meaningful help you have to ask a meanginful question :) -- Andrue Cope [TeamB] [Bicester, Uk] http://info.borland.com/newsgroups/guide.html Back to top Marco Guest Posted: Mon Mar 07, 2005 11:04 am    Post subject: Re: FILE Problem This is an example of my code: //------------------------------------------------------------- void TCompCodici::SaveFile() { FILE *file = fopen (".\Cfg\CompCod.dat", "w"); if (file == NULL) { ShowMessage("Error! Can't open file CompCod.dat"); return; } fprintf (file, "[Costanti compilatore]n"); fprintf (file, "NrCodici=%dn",FLista.Count()); for (int i=0; i fprintf (file, "%d=%sn",FLista[i]); fclose (file); } //-------------------------------------------------------------void TCompCodici::OpenFile() { char szBuff[121]; int i = 0; FILE *file = fopen (".\Cfg\CompCod.dat", "rt"); if (file == NULL) { ShowMessage("Error! Can't open file CompCod.dat"); return; } while (!feof(file)) { fgets(szBuff, 120, FMsgFile); FLista[i] = szBuff; i++; } } //------------------------------------------------------------- FLista is a stringlist. My problem is that if i try to open file on my PC sometimes error occours but if i copy all my folder on another PC all work correctly (always). Could WinXP (API or somethingelse) give the problem? Thanks. Marco Back to top Hans Galema Guest Posted: Mon Mar 07, 2005 11:13 am    Post subject: Re: FILE Problem Marco wrote: Quote: FILE *file = fopen (".\Cfg\CompCod.dat", "w"); FILE *file = fopen (".\Cfg\CompCod.dat", "rt"); My problem is that if i try to open file on my PC sometimes error occours Please explain exactly what kind of error. Why must we guess ? But I think that the file can not be found because you use relative paths. Better use absolute paths. Hans. Back to top Andrue Cope [TeamB] Guest Posted: Mon Mar 07, 2005 11:31 am    Post subject: Re: FILE Problem Marco wrote: Quote: My problem is that if i try to open file on my PC sometimes error occours but if i copy all my folder on another PC all work correctly (always). Could WinXP (API or somethingelse) give the problem? FILE *file = fopen (".\Cfg\CompCod.dat", "w"); if (file == NULL) { ShowMessage("Error! Can't open file CompCod.dat"); return; } Oh dear, oh dear - I see so many programs that handle file I/O like that. Even Borland are guilty of that kind of sloppy I/O implementation. I/O operations usually provide a mechanism for obtaining an error code and if they don't IMO programmers shouldn't use them :) In this case Borland's help seems to be a bit poor. The help for fopen() doesn't bother to mention 'errno'. This variable will contain an error code from whatever runtime library function last failed. You even get a textual message for a code by using it as an index into the '_sys_errlist' array. Alternatively if you are coding for Windows you can just use GetLastError() - this should probably be your first port of call when you get any kind of I/O or API related problems. If you are using the VCL it can be combined with SysErrorMsg() to get a system error message for a system error code. If you aren't using the VCL you can use FormatMessage(): // From the help LPVOID lpMsgBuf; FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language (LPTSTR) &lpMsgBuf, 0, NULL ); // Display the string. MessageBox( NULL, lpMsgBuf, "GetLastError", MB_OK|MB_ICONINFORMATION ); // Free the buffer. LocalFree( lpMsgBuf ); Try changing your code to be: FILE *file = fopen (".\Cfg\CompCod.dat", "w"); if (file == NULL) { ShowMessage("Error! Can't open file CompCod.dat:"+ SysErrorMsg( GetLastError() ) ); return; } And see what reason is given. One other thing that I also dissapprove of is your use of a relative path in a call to fopen(). It's okay (essential in fact) if you have a collection of files that all relate to each other (such as a project group) but then the path should be relative to a central file and should be resolved into a fully qualified path internally at the first opportunity. Several serious faults with the BCB IDE can be attributed to Borland programmers using relative paths and not resolving them. -- Andrue Cope [TeamB] [Bicester, Uk] http://info.borland.com/newsgroups/guide.html Back to top Marco Guest Posted: Mon Mar 07, 2005 11:58 am    Post subject: Re: FILE Problem Hans wrote: Quote: But I think that the file can not be found because you use relative paths. Better use absolute paths. Thank you Hans, absolute path resolve my problem. HAndrue wrote: Quote: Oh dear, oh dear - I see so many programs that handle file I/O like that. Even Borland are guilty of that kind of sloppy I/O implementation. I/O operations usually provide a mechanism for obtaining an error code and if they don't IMO programmers shouldn't use them I'm terrible sorry, i'm not a really programmer but i would want to become it. From now I will write a better code, thank you very much. Marco Back to top Wiljo Guest Posted: Mon Mar 07, 2005 12:00 pm    Post subject: Re: FILE Problem Marco wrote: Quote: This is an example of my code: FILE *file = fopen (".\Cfg\CompCod.dat", "w"); I also concur that you shouldn't use relative paths, unless you are absolutely sure what the current directory is. But when your program is moved to another directory in the future, your program might fail again! Quote: ..... for (int i=0; i fprintf (file, "%d=%sn",FLista[i]); Here is another mistake, or probably a typo. The fprintf statement contains the format "%d=%sn", specifying two additional arguments (one for %d and one for %s). Only the latter one is given. Another suggestion for the file reader: Quote: while (!feof(file)) { fgets(szBuff, 120, FMsgFile); FLista[i] = szBuff; i++; } You can replace this by while( fgets( szBuff, 120, FMsgFile )) { FLista[i] = szBuff; ++i; } The fgets function can be used to test for eof. Or, because FLista is a string list, why don't you use the LoadFromFile member function of the string list component itself? Wiljo. Back to top Andrue Cope [TeamB] Guest Posted: Mon Mar 07, 2005 12:17 pm    Post subject: Re: FILE Problem Marco wrote: Quote: I'm terrible sorry, i'm not a really programmer but i would want to become it. From now I will write a better code, thank you very much. My response was intended to be a lighthearted comment (as indicated by the '' at the end) so I hope you haven't taken offense at it. As regards becoming a real programmer you needn't worry. Plenty of real programmers neglect to give appropriate diagnostic information to their users. Sometimes they give too much but mostly they just don't give enough. In this case whoever wrote the help didn't do you any favours because they neglected to mention 'errno'. -- Andrue Cope [TeamB] [Bicester, Uk] http://info.borland.com/newsgroups/guide.html Back to top Marco Guest Posted: Mon Mar 07, 2005 12:52 pm    Post subject: Re: FILE Problem Quote: Andrue wrote: My response was intended to be a lighthearted comment (as indicated by the '' at the end) so I hope you haven't taken offense at it. I haven't taken it like offense. I like very much this "forum" for the friendly atmosphere and i have interpreted your comment like the comment of an expert friend. Thank you for all. 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