Re: [C and C++] && Operator precedence

Aggro wrote:
> I would like to know the answer to this for both C and C++ as I use both
> languages (usually in differen projects).
> 
> Assume the code
> if( A && B )
> 
> Normally A is executed before B 

No. If A yields false, B is not executed at all. This is called
short-circuit evaluation. Note that in C++ you are actually able to
override operator && and then it's a normal function call which means that
both arguments are evaluated, though their order is unspecified.


> But recently I got second hand information that the execution order is
> not quaranteed. E.g. B could be executed before A by some compilers.

Not by conforming ones, due to the short-circuit rule.

> Different execution order could cause e.g. application to crash if we
> first test is the pointer valid and then call a function for that
pointer:
> if( p && p->func() )

This code is fine.

I would try to limit use of this feature though, because it has rather
surprising semantics. Above example is IMHO okay though.

Uli