🚀 go-pugleaf

kremser@sbox.tu-graz.ac.at (Herbert Kremser) writes:
>If i see

>  if (p != NULL && p->is_ok != 0)

>i have to think a bit longer what really is meant, compared to

>  if (p && p->is_ok)

Here I prefer 
 if( p!= NULL && p->is_ok )

because
 p represents a pointer which may conatain any value
 p->is_ok represents a boolean value (yes, I know there is
 no boolean type in C) which can either be 0 (False) or not 0 (True).


>Ok, no ! in here, so

>  if (p == NULL || p->is_ok == 0)
>compared to
>  if (!p || !p->is_ok)

This is no good example as the second part of the if clause
will dereference a NULL pointer which fails on "real Systems".

Taking
 if( p == certain_pointer || p->is_ok == 0 )
I would take
 if( p == certain_pointer || !p->is_ok )

You see the problem? p cannot be checked sensfully in terms of
equal or not equal.

h.f.s.
--
Hans Friedrich Steffani
Institut fuer Elektrische Maschinen und Antriebe
TU Chemnitz-Zwickau
e-mail: hans.steffani@e-technik.tu-chemnitz.de