Re: [avr-gcc-list] possible compiler/optimizer problem (?)

[Ned Konz]

Gary Douglas wrote:

> Not sure if this is a bug, or if what I'm trying to do is just incorrect 
> C syntax.  Regardless, the compiler doesn't warn about the following:
[snip]
>     value != value;//This is the problem line - always true   
[snip]
> If I change it to this it works:
[snip]
>     value = (!value); //This works...
[snip]
> Are these not fundamentally the same?

No.

value != value;

is just a Boolean expression (which should always be false, but since 
its value is not used, the compiler probably throws the test away); it's 
not an assignment.

What probably is confusing is that C provides some composite 
operator/assignment operators:

+= -= *= /= &= |= ^= %= <<= >>=

but != is one of the test operators that happen to end in '=':

!= == >= <=

--
Ned Konz