Christopher Smith wrote:
Tracy R Reed wrote:
I'm with Gus on this one. The number you get when you print a
reference might look like a big number typical of a memory location
but if you reference a different number that you pick at random do you
generally get a segfault?
It isn't necessary that you get a segfault, so long as you get an error
of some kind. Segfaults are just a more painful way of telling you that
you've screwed up (unless you are doing pointer swizzling).
--Chris
the thing that most people find hard to get about such errors, is their
non-deterministic nature. when you screw up your memory - sometimes you
don't see any effect, because you accessed mapped-yet-unused memory.
sometimes you access un-mapped memory (i.e. memory not mapped in the
virtual address space of the process) - and then you get a seg fault.
sometimes you access memory that is maarked as read-only (when you try
to write) or as no-read-no-write (such as page zero) - and you also get
a seg fault. sometimes you access memory that is used by the program for
a different purpose - and then you don't get any seg fault - because the
address is mapped. you screw something in memory that will only become
evident later in the program.
people expect computer programs to be deterministic - but bugs are
non-deterministic, by nature.
--guy
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