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Why does this example C code run and yet SHOULD either not compile or give a segmentation fault?

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Top Forums Programming Why does this example C code run and yet SHOULD either not compile or give a segmentation fault?
# 15  
Old 03-28-2019
Quote:
Originally Posted by Corona688
It's necessary sometimes, if you're building an operating system for example, to insert special instructions here and there without the compiler's interference. That's the kind of thing asm() is for. gcc will insert raw assembly if you ask, but you really have to know what you're doing since it can't protect you( though some more advanced syntax lets you warn gcc about side-effects instead). Plain, non-ASM goto (yes, it exists, very rarely used) wouldn't let you jump out of bounds.
As I have said in the distant past that I have coded assembly in 16 and 32 bit intel architecture but no experience in 64 bit, although I suspect there is not much difference.
And, I would only use it for mission critical stuff of which these days there is no need as HW interface APIs are usually far more than good enough for this purpose especially as the UNIX ethos is that everything is a file.

One thing for sure I am getting to know how gcc __thinks__ and compared to say Dice-C or VBCC for the AMIGA it is mega-powerful.
And finally I know that 'goto' is local to the function that uses it, and a good thing it is too.
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LEARN ABOUT DEBIAN

itksnap

ITKSNAP(1)							   User Commands							ITKSNAP(1)

NAME

       itksnap - semi-automatic segmentation of structures in 3D images

SYNOPSIS

       itksnap [options] [grey_image]

DESCRIPTION

       SNAP  provides semi-automatic segmentation of structures in medical images (e.g.  magnetic resonance images of the brain) using active con-
       tour methods, as well as manual delineation and image navigation.  Noteworthy features are:

       * Linked cursor for seamless 3D navigation

       * Manual segmentation in three orthogonal planes at once

       * Support for many different 3D image formats, including NIfTI

       * Support for concurrent, linked viewing and segmentation of multiple images

       * Limited support for color images (e.g., diffusion tensor maps)

       * 3D cut-plane tool for fast post-processing of segmentation results

OPTIONS

       --grey, -g FILE
	      Load greyscale image FILE (optional)

       --segmentation, -s FILE
	      Load segmentation image FILE

       --labels, -l FILE
	      Load label description file FILE

       --rgb FILE
	      Load RGB image FILE (as overlay if combined with -g)

AUTHOR

       ITK-SNAP was written by Paul A. Yushkevichi, Hui Zhang, Casey Goodlett, Timothy Burke, Nicholas	Tustison,  Guido  Gerig,  Silvio  Turello,
       Joachim	Schlegel,  Gabor Szekely, Chris Wynn, Arun Neelamkavil, David Gregg, Eric Larsen, Sanjay Sthapit, Sean Ho, Ashraf Farrag, Amy Hen-
       derson, Robin Munesato, Ming Yu, Nathan Moon, Thorsten Scheuermann, Konstantin Bobkov, Nathan Talbert, Yongjik Kim, Pierre Fillard,  Daniel
       S. Fritsch, Stephen R. Aylward

       This manual page was written by Michael Hanke <michael.hanke@gmail.com>, for the Debian project (but may be used by others).

SEE ALSO

       Manual and tutorial: http://itksnap.org

Michael Hanke							    April 2010								ITKSNAP(1)