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IWETHEY Home / IWETHEY Board / Theory and Practice of Programming Forum / It does
Post #98,266
by tjsinclair
4/23/03 1:51:03 PM
Reply
New It does
The original open() call was erroring out.

The code just didn't catch the error and was blithely assuming that the file existed and was open for I/O.

Tom Sinclair

"Man, I love it when the complete absence of a plan comes together."
- [link|http://radio.weblogs.com/0104634/|Ernie the Attorney]
Post #98,328
by tuberculosis
Picture of tuberculosis
4/23/03 3:57:18 PM
8/21/07 5:40:03 AM
Reply
New Erroring out?
I didn't see a try/catch construct in the code and you didn't mention the output so I figured it was silently failing and doing nothing.

Do you get an "uncaught exception" message?


"Packed like lemmings into shiny metal boxes.
Contestants in a suicidal race."
    - Synchronicity II - The Police
Expand Edited by tuberculosis Aug. 21, 2007, 05:40:03 AM EDT
Expand All History
Post #98,338
by tjsinclair
4/23/03 4:14:13 PM
Reply
New I checked the ios error flags
Basically I added a check for datafile.fail() and dumped it out if this returned true.

I only needed to verify if and where it was failing so exceptions would have been (to my mind) overkill.

When I checked the flags immediately after the open() call, the failbit flag was set but the original code didn't look for that so it went merrily on its way, assuming all was well.

As I said, this is code written by the textbook author and it apparently works without modification on Windows.
Tom Sinclair

"Man, I love it when the complete absence of a plan comes together."
- [link|http://radio.weblogs.com/0104634/|Ernie the Attorney]
Post #98,346
by tuberculosis
Picture of tuberculosis
4/23/03 4:30:00 PM
8/21/07 5:40:22 AM
Reply
New Thats not raising an exception
that's hiding an error code somewhere you have to go dig for it.

Its akin to returning an error code from a function - and of course nobody checks the return codes from functions - which is why exceptions were invented.


"Packed like lemmings into shiny metal boxes.
Contestants in a suicidal race."
    - Synchronicity II - The Police
Expand Edited by tuberculosis Aug. 21, 2007, 05:40:22 AM EDT
Expand All History
Post #98,347
by tjsinclair
4/23/03 4:34:47 PM
Reply
New Agreed
Exceptions are a better solution to the problem.
Tom Sinclair

"Man, I love it when the complete absence of a plan comes together."
- [link|http://radio.weblogs.com/0104634/|Ernie the Attorney]
     C++ File I/O: Windows vs. Linux - (tjsinclair) - (85) - April 23, 2003, 12:50:26 AM EDT
         Wild guess - (JayMehaffey) - (1) - April 23, 2003, 01:39:26 AM EDT
             Nope - (tjsinclair) - April 23, 2003, 01:57:23 AM EDT
         Permissions problem? - (tuberculosis) - (16) - April 23, 2003, 02:03:13 AM EDT
             Possibly - (tjsinclair) - (15) - April 23, 2003, 09:16:35 AM EDT
                 The only dumb question is... - (jbrabeck) - (14) - April 23, 2003, 09:41:05 AM EDT
                     Thanks - (tjsinclair) - (13) - April 23, 2003, 09:57:18 AM EDT
                         I'd second the permissions... - (jbrabeck) - (12) - April 23, 2003, 10:04:41 AM EDT
                             Played with error bits - (tjsinclair) - (11) - April 23, 2003, 10:20:42 AM EDT
                                 C++ for real work - (tuberculosis) - (10) - April 23, 2003, 12:53:07 PM EDT
                                     telco's use lots of c++ -NT - (boxley) - (7) - April 23, 2003, 01:21:19 PM EDT
                                         on UNIX? - (tjsinclair) - (6) - April 23, 2003, 01:51:47 PM EDT
                                             well several softswitches and other software (added link) - (boxley) - (2) - April 23, 2003, 07:40:08 PM EDT
                                                 Yeah - OS level code I think - (tuberculosis) - (1) - Aug. 21, 2007, 05:40:10 AM EDT
                                                     Stacked based types? - (deSitter) - April 23, 2003, 11:22:58 PM EDT
                                             some more info on c++ Unix and Telcos and jobs - (boxley) - (2) - April 24, 2003, 01:26:19 PM EDT
                                                 CORBA == Objects, so makes sense - (tjsinclair) - April 24, 2003, 04:14:39 PM EDT
                                                 Resume mailed -NT - (tuberculosis) - Aug. 21, 2007, 05:47:21 AM EDT
                                     Someone somewhere must be using it - (tjsinclair) - April 23, 2003, 01:49:28 PM EDT
                                     Network Management software - (Arkadiy) - April 24, 2003, 03:18:49 PM EDT
         I don't know C++ but... - (ben_tilly) - (6) - April 23, 2003, 06:54:46 AM EDT
             Seems like it ought to raise an exception on failure -NT - (tuberculosis) - (5) - April 23, 2003, 12:55:01 PM EDT
                 It does - (tjsinclair) - (4) - April 23, 2003, 01:51:03 PM EDT
                     Erroring out? - (tuberculosis) - (3) - Aug. 21, 2007, 05:40:03 AM EDT
                         I checked the ios error flags - (tjsinclair) - (2) - April 23, 2003, 04:14:13 PM EDT
                             Thats not raising an exception - (tuberculosis) - (1) - Aug. 21, 2007, 05:40:22 AM EDT
                                 Agreed - (tjsinclair) - April 23, 2003, 04:34:47 PM EDT
         Got it! - (tjsinclair) - (58) - April 23, 2003, 10:29:50 AM EDT
             Now, this is really scary - (Arkadiy) - (53) - April 24, 2003, 03:36:51 PM EDT
                 Even scarier - (tjsinclair) - (52) - April 24, 2003, 04:16:21 PM EDT
                     At this point, one wants to,, - (deSitter) - (3) - April 24, 2003, 05:06:14 PM EDT
                         Ross, do we need a refresher... - (jb4) - (2) - April 28, 2003, 06:18:53 PM EDT
                             I would completely agree with you except - (tjsinclair) - (1) - April 28, 2003, 10:17:18 PM EDT
                                 Wow! - (jb4) - April 29, 2003, 01:14:14 PM EDT
                     Which version of gcc? - (admin) - April 24, 2003, 05:14:30 PM EDT
                     So, let me get this straight... - (Arkadiy) - (46) - April 24, 2003, 05:25:12 PM EDT
                         Something like that, yes - (tjsinclair) - (44) - April 25, 2003, 01:57:53 AM EDT
                             I've been trying to do that for years - (tuberculosis) - Aug. 21, 2007, 05:47:23 AM EDT
                             Barney is not responsible... - (jb4) - (42) - April 28, 2003, 06:22:39 PM EDT
                                 Move farther up the food chain - (tuberculosis) - (41) - Aug. 21, 2007, 06:14:23 AM EDT
                                     OK, I'll bite... - (jb4) - (39) - May 2, 2003, 10:11:02 AM EDT
                                         Errr... - (admin) - (34) - May 2, 2003, 10:40:54 AM EDT
                                             I've heard strong typing called several different things... - (jb4) - (33) - May 2, 2003, 04:43:33 PM EDT
                                                 Strict typing is like training wheels. - (admin) - (32) - May 2, 2003, 05:00:44 PM EDT
                                                     Re: Strict typing is like training wheels. Or Helmuts? - (jb4) - (31) - May 2, 2003, 05:43:56 PM EDT
                                                         You have much to learn - (tuberculosis) - (23) - Aug. 21, 2007, 06:25:06 AM EDT
                                                             Irony - (ben_tilly) - (22) - May 3, 2003, 11:06:01 AM EDT
                                                                 Additionally... - (admin) - (21) - May 3, 2003, 12:47:45 PM EDT
                                                                     That's the C++ propaganda - (tuberculosis) - (20) - Aug. 21, 2007, 06:28:02 AM EDT
                                                                         Wrong usage - (Arkadiy) - (7) - May 5, 2003, 02:48:10 PM EDT
                                                                             Return value problem - (tuberculosis) - (6) - Aug. 21, 2007, 06:33:56 AM EDT
                                                                                 I'll take a look for the solution for ret value - (Arkadiy) - May 5, 2003, 07:30:55 PM EDT
                                                                                 Re: Return value problem - (deSitter) - (4) - May 5, 2003, 10:19:41 PM EDT
                                                                                     In the end - (Arkadiy) - (3) - May 6, 2003, 09:17:21 AM EDT
                                                                                         A better statically typed language - have you tried Haskell? -NT - (ben_tilly) - (1) - May 7, 2003, 05:13:57 AM EDT
                                                                                             Read the tutorials - (tuberculosis) - Aug. 21, 2007, 12:41:27 PM EDT
                                                                                         Today's link at /. - (Arkadiy) - May 8, 2003, 07:32:39 PM EDT
                                                                         Interesting example, Todd - (jb4) - (11) - May 6, 2003, 05:26:41 PM EDT
                                                                             Umm... - (Simon_Jester) - (5) - May 6, 2003, 02:15:24 PM EDT
                                                                                 And what would you cast the void* back to afterwards? -NT - (tuberculosis) - (4) - Aug. 21, 2007, 06:38:46 AM EDT
                                                                                     Yeah, you'd have to test for the type... - (Simon_Jester) - (3) - May 6, 2003, 06:47:54 PM EDT
                                                                                         Aaaaaahhhhhhh! - (tuberculosis) - (2) - Aug. 21, 2007, 06:39:11 AM EDT
                                                                                             *chuckle* - (Simon_Jester) - (1) - May 6, 2003, 09:46:44 PM EDT
                                                                                                 Oh, you illustrated several problems - (tuberculosis) - Aug. 21, 2007, 06:39:47 AM EDT
                                                                             Your code should crash - (tuberculosis) - (4) - Aug. 21, 2007, 06:38:33 AM EDT
                                                                                 My code does crash, but not as often as you think. - (jb4) - (3) - May 6, 2003, 06:01:00 PM EDT
                                                                                     Re: My code does crash, but not as often as you think. - (admin) - (1) - May 6, 2003, 06:04:08 PM EDT
                                                                                         Replies coming - (jb4) - May 7, 2003, 06:57:16 PM EDT
                                                                                     Re: My code does crash, but not as often as you think. - (tuberculosis) - Aug. 21, 2007, 06:39:07 AM EDT
                                                         Finally, something other than hand-waving. - (admin) - (6) - May 2, 2003, 07:51:43 PM EDT
                                                             Hey I know Java - (tuberculosis) - (3) - Aug. 21, 2007, 06:25:18 AM EDT
                                                                 Whoops, forgot that one. - (admin) - (2) - May 2, 2003, 07:46:45 PM EDT
                                                                     I always sit on a towel when using it - (tuberculosis) - (1) - Aug. 21, 2007, 06:25:43 AM EDT
                                                                         Interesting... I find I get more use out of... - (admin) - May 2, 2003, 09:40:13 PM EDT
                                                             I've done it - (Arkadiy) - (1) - May 5, 2003, 03:03:42 PM EDT
                                                                 Re: I've done it - (admin) - May 6, 2003, 02:36:03 PM EDT
                                         How? - (tuberculosis) - (3) - Aug. 21, 2007, 06:23:01 AM EDT
                                             Erm? - (jb4) - (2) - May 6, 2003, 01:30:58 PM EDT
                                                 GNU CPP version 2.95.2 19991024 (release) -NT - (tuberculosis) - (1) - Aug. 21, 2007, 06:38:43 AM EDT
                                                     Sorry to hear that...:-( - (jb4) - May 6, 2003, 06:02:41 PM EDT
                                     Well said, exactly correct -NT - (deSitter) - May 2, 2003, 10:59:37 AM EDT
                         This is frigging runtime lib bug, not language - (Arkadiy) - April 25, 2003, 01:02:52 PM EDT
             You were mis-using the flags... - (Simon_Jester) - (3) - April 25, 2003, 03:05:57 PM EDT
                 I thought of that - (tjsinclair) - (2) - April 25, 2003, 04:25:46 PM EDT
                     For what it's worth, code also runs... - (a6l6e6x) - (1) - April 25, 2003, 04:47:48 PM EDT
                         Figured that -NT - (tjsinclair) - April 25, 2003, 06:27:33 PM EDT

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