Solved

Linux atof problem

Posted on 1997-04-30
3
453 Views
Last Modified: 2013-12-26
I have a C++ program that reads in a binary string, parses it into character arrays and converts some of them to doubles with atof.  It works fine on the Sun Sparcs on which the data is stored.  However, when I compile and run the program on Linux, the program bombs.  After debugging with gdb, I found that a string goes into atof as "1201" and comes out as 12019.  The Linux system nfs mounts the data disk from the same Sun.  I examined the "1201" in binary form, and it looks the same as on the Sun.

Thanks in advance.
0
Comment
Question by:jshirer
  • 2
3 Comments
 
LVL 3

Accepted Solution

by:
dhm earned 100 total points
ID: 1292728
Do you #include a header file that declares "double atof(const char *)"?  (Either <stdlib.h>, <fbm.h>, or some file that indirectly includes one of them.)  If not, you may be getting bitten by a return-type conversion bug.

Otherwise, check that the "1201" string is really '\0'-terminated.  If there's some other byte at the end of the string, it's possible that the Linux atof is attempting to continue conversion further than it should, while the Sun is stopping at the first non-numeric character.

(I just ran a test program on Linux here; I found that if you don't declare atof(), you get a bogus result, but if you do, you get the correct result -- even if there's a garbage character at the end of the string you convert.)
0
 

Author Comment

by:jshirer
ID: 1292729
Thanks!  There was another byte at the end of the string.  The string was created with the strncpy, not strcpy.  The strncpy on the sun put '/000' as the last byte.  Linux put '9', for whatever reason.  I just had to specify that the last byte = '\0', and it worked!  There are a lot of happy people here now.
0
 
LVL 3

Expert Comment

by:dhm
ID: 1292730
It's unlikely that the strncpy put the "9" there; strncpy copies only as many bytes as you tell it to.  Probably, the buffer you were copying into was uninitialized (i.e. contained garbage), and the garbage on the Sun just happened to be '\0', while on Linux it was '9'.  Gotta watch those memcopy-type functions :-)
0

Featured Post

Master Your Team's Linux and Cloud Stack!

The average business loses $13.5M per year to ineffective training (per 1,000 employees). Keep ahead of the competition and combine in-person quality with online cost and flexibility by training with Linux Academy.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Expand to include initial dialog with two choices. 9 78
lucky13 challenge 11 144
tripleUp challenge 7 79
withoutTen challenge 14 122
Here is how to use MFC's automatic Radio Button handling in your dialog boxes and forms.  Beginner programmers usually start with a OnClick handler for each radio button and that's just not the right way to go.  MFC has a very cool system for handli…
Introduction: Dynamic window placements and drawing on a form, simple usage of windows registry as a storage place for information. Continuing from the first article about sudoku.  There we have designed the application and put a lot of user int…
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Two types of users will appreciate AOMEI Backupper Pro: 1 - Those with PCIe drives (and haven't found cloning software that works on them). 2 - Those who want a fast clone of their boot drive (no re-boots needed) and it can clone your drive wh…

778 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question