Re: Implementation-defined behaviour

Ioannis Vranos wrote:
> 
> Andrey Tarasevich wrote:
> > Ioannis Vranos wrote:
> >> So, printf("%d "%d\n", x++, x++); invokes implementation-defined
> >> behaviour, while printf("%d\n", x++); doesn't invoke
> >> implementation-defined behaviour?
> >
> > 'printf("%d "%d\n", x++, x++)' invokes _undefined_ behavior.
'printf("%d
> > "%d\n", x++, x)' also invokes _undefined_ behavior.
> >
> > 'printf("%d\n", x++)' does not invoke undefined behavior.
> >
> > "Implementation-defined behavior" is not immediately relevant to the
> > nature of your question.
> 
> K&R2 mentions the following:
> 
> "printf("%d %d\n", ++n, power(2,n));   /* WRONG */
> 
> can produce different results with different compilers, depending on
> whether n is incremented before power is called".
> 
> That's why I call it implementation-defined behaviour.

It's unspecified behavior.
The power(2,n) function call, introduces a sequence point 
that the other code examples don't have.
This is all about sequence points.

-- 
pete