nonportable code or incorrect compilers?

[Doug Gwyn]

In article <376 at accelerator.eng.ohio-state.edu> rob at kaa.eng.ohio-state.edu (Rob Carriere) writes:
>However, the conversion rule says that a is to be
>converted to double; this seems to contradict the idea that a is to be
>computed *once*.

That's not the rule.

	a op= b

(where a and b are expressions) is equivalent to

	a = a op b

EXCEPT that the expression a is EVALUATED only once.
I.e. if evaluation of the expression a has side-effects,
they will occur only once.
Once the expression is evaluated, it is used in the context

	a = a op b

and other stuff happens at that point.