volatile required?

[Barry Margolin]

In article <712 at Aragorn.dde.dk> ct at dde.dk (Claus Tondering) writes:
>	  int p=3, *q=&p;
>	  *q=4;
>	  printf("%d\n",p);
>Is it acceptable that this program prints 3 instead of 4? The variable
>p is not declared volatile, and therefore the fact that *q=4 assigns
>4 to p may be considered a side effect.

No, the program must print 4.  Since p's address is taken, the
optimizer should know that it isn't safe to assume that only
assignments to p will modify its value.

Barry Margolin, Thinking Machines Corp.

barmar at think.com
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