:: Re: [DNG] [OT] [Re: Studying C as t…
Página Principal
Delete this message
Reply to this message
Autor: KatolaZ
Data:  
Para: Edward Bartolo
CC: dng
Assunto: Re: [DNG] [OT] [Re: Studying C as told. (For help)
On Tue, Jun 21, 2016 at 08:22:41AM +0200, Edward Bartolo wrote:

[cut]

>
> I studied 'and' and 'or' boolean operators back when I studied Delphi
> Pascal. I am embarrassed to have written such a stupid thing. It must
> be due to the fact I wrote the email just before going to bed.
>
> AND: requires ALL sub-expressions to be true to evaluate to true
> i.e.   Q = A ^ B ^ C ^ .... D
>         Q = 1 if and only if A = B = C = .... D = 1

>
> OR: only requires ONE sub-exression to be true to evaluate to true
> i.e.   Q = A v B v C v .... D
>         Q = 1 if any Ai = 1

>
> These properties are used by compilers to optimize on boolean
> expression evaluation. If I remember well, there are also specific


Be careful, because conditional expressions in C are subject to
"short-circuiting", meaning that only the minimum number of
expressions sufficient to determine the value of a chain of && and ||
will be evaluated. In particular, a chain of || expressions will be
evaluated until there is one that evaluates to TRUE (!=0), while a
chain of && is evaluated until there is one of them which evaluates to
false (==0).

HND

KatolaZ

-- 
[ ~.,_  Enzo Nicosia aka KatolaZ - GLUGCT -- Freaknet Medialab  ]  
[     "+.  katolaz [at] freaknet.org --- katolaz [at] yahoo.it  ]
[       @)   http://kalos.mine.nu ---  Devuan GNU + Linux User  ]
[     @@)  http://maths.qmul.ac.uk/~vnicosia --  GPG: 0B5F062F  ] 
[ (@@@)  Twitter: @KatolaZ - skype: katolaz -- github: KatolaZ  ]