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

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