Re: Word alignment - Why doesn't this crash?

ollemblomgren@xxxxxxxxx wrote:
I try to confirm my understanding of word alignment by writing a
program that screw this particular matter up.

I run linux on:
Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz

my compiler is:
gcc version 4.1.2

I compile with no arguments other than source file name and target
name (-o ptr_test).

I write this program but it doesn't crash. Is it because I'm testing
the wrong thing (my understanding is wrong) or is it because my
environment is very forgiving?

Your program exhibits undefined behaviour. The answer to FAQ 11.35 is relevant (and much better written than anything I write):

A compiler may do anything it likes when faced with undefined
behavior (and, within limits, with implementation-defined and
unspecified behavior), including doing what you expect. It's unwise
to depend on it, though.

Here is another way of looking at it, due to Roger Miller:

``Somebody told me that in basketball you can't hold the ball and
run. I got a basketball and tried it and it worked just fine. He
obviously didn't understand basketball.''

It seems your implementation doesn't mind that particular alignment issue. C doesn't say that alignment issues /will/ happen, only that they /might/.

Philip

.

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