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Full Discussion: Why does this example C code run and yet SHOULD either not compile or give a segmentation fault?
Top Forums Programming Why does this example C code run and yet SHOULD either not compile or give a segmentation fault? Post 303033033 by wisecracker on Thursday 28th of March 2019 08:23:19 PM
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

cxref-cpp

cxref-cpp(1)						      General Commands Manual						      cxref-cpp(1)

NAME

       cxref-cpp - A modified C preprocessor to use with cxref.

SYNOPSIS

       cxref-cpp ...

DESCRIPTION

       To  improve  the  output  that  is available for the source code for cross-referencing a modified version of the GNU CPP v2.7.2 is supplied
       (named cxref-cpp).

       This modified C preprocessor allows for a finer control over some features of the preprocessing that are not important for a compiler.	In
       a  standard  preprocessor, the preprocessor directives are intended for use only by the preprocessor, so passing the information through is
       not important.

       With cxref-cpp, there are some features that are different to the standard GNU CPP:

	      Compared to gcc versions earlier than version 2.8.0 there is an extra option that will output the #include  lines  from  the  source
	      file.  In version 2.8.0 and later this option is present.

	      Comments	trailing  a  #include  or  a  #define are not preserved by all versions of gcc even if the -C option is used.  This is not
	      important while compiling, but is useful for documenting.

	      The cxref-cpp program will take on the personality of the installed version of gcc so that the gcc header files can be parsed.  This
	      means  that it includes the same default include directory paths and macro definitions.  The file that contains these definitions is
	      called cxref-cpp.defines and is installed by the cxref-cpp-configure program or specified by  the  -cxref-cpp-defines  command  line
	      option.

OPTIONS

       The same as for gcc, apart from '-cxref-cpp-defines' described above.

SEE ALSO

       cxref(1), cxref-cpp-configure(1), gcc(1)

								    May 9, 2004 						      cxref-cpp(1)
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