🚀 go-pugleaf

In article <4jol5v$1qs@solutions.solon.com>, wawda@chaph.usc.edu says...
>
>After reading the thread on "Good C interview questions", I've got to
>ask people to post some tricky/trivia questions on programming in C or
>even programming in general. Does anyone have any? Thanks in advance.
>
>Abu Wawda
>wawda@scf.usc.edu

Here's a little example of C's inconsistent syntax:

int * i, * j, k;

k = *i/*j;

In article <4jol5v$1qs@solutions.solon.com> wawda@chaph.usc.edu (Abu Wawda) writes:
>After reading the thread on "Good C interview questions", I've got to
>ask people to post some tricky/trivia questions on programming in C or
>even programming in general. Does anyone have any? Thanks in advance.

How about explaining what following construct does. What can be said about the
values of l and i at the end?

    size_t l;
    int i = MAXINT;

    l = sizeof(++i);

:-)

	James
--
James Bonfield (jkb@mrc-lmb.cam.ac.uk)   Tel: 01223 402499   Fax: 01223 412282
Medical Research Council - Laboratory of Molecular Biology,
Hills Road, Cambridge, CB2 2QH, England.

In article <4jttdi$3jm@solutions.solon.com>
           jkb@mrc-lmb.cam.ac.uk "James Bonfield" writes:

>In article <4jol5v$1qs@solutions.solon.com> wawda@chaph.usc.edu (Abu Wawda)
> writes:
>>After reading the thread on "Good C interview questions", I've got to
>>ask people to post some tricky/trivia questions on programming in C or
>>even programming in general. Does anyone have any? Thanks in advance.
>
>How about explaining what following construct does. What can be said about the
>values of l and i at the end?
>
>    size_t l;
>    int i = MAXINT;
>
>    l = sizeof(++i);
>
>:-)

Very little since MAXINT isn't defined. :-) Perhaps if you were to include
limits.h and use INT_MAX instead. If you want to add a bit of interest to
the problem you could ask the same question about:

#include <stddef.h>
#include <limits.h>

    size_t l;
    short i = SHRT_MAX;

    l = sizeof(++i);

-- 
-----------------------------------------
Lawrence Kirby | fred@genesis.demon.co.uk
Wilts, England | 70734.126@compuserve.com
-----------------------------------------

In article <4k1pks$514@solutions.solon.com>,
Lawrence Kirby  <fred@genesis.demon.co.uk> wrote:
 >In article <4jttdi$3jm@solutions.solon.com>
 >           jkb@mrc-lmb.cam.ac.uk "James Bonfield" writes:
 >
 >>In article <4jol5v$1qs@solutions.solon.com> wawda@chaph.usc.edu (Abu Wawda)
 >> writes:
 >>>After reading the thread on "Good C interview questions", I've got to
 >>>ask people to post some tricky/trivia questions on programming in C or
 >>>even programming in general. Does anyone have any? Thanks in advance.
 >>
 >>How about explaining what following construct does. What can be said about the
 >>values of l and i at the end?
 >>
 >>    size_t l;
 >>    int i = MAXINT;
 >>
 >>    l = sizeof(++i);
 >>
 >>:-)
 >
 >Very little since MAXINT isn't defined. :-) Perhaps if you were to include
 >limits.h and use INT_MAX instead. If you want to add a bit of interest to
 >the problem you could ask the same question about:
 >
 >#include <stddef.h>
 >#include <limits.h>
 >
 >    size_t l;
 >    short i = SHRT_MAX;
 >
 >    l = sizeof(++i);

Whatever the case, one can always say l==sizeof(i) (the actual numerical
value is implementation dependant), and i remains unchanged from it's
initial value, whether that's MAXINT, INT_MAX, SHRT_MAX, FOO, 5, etc. I
think the original poster's point was that the above code does not change
the value of i, which is not obvious unless you know that sizeof does not
evaluate it's operand.

-- 
        Carl Laurence Gonsalves - clgonsal@undergrad.math.uwaterloo.ca
                   Computer Science, University of Waterloo
               http://www.undergrad.math.uwaterloo.ca/~clgonsal/
                   http://www.csclub.uwaterloo.ca/~clgonsal/

wawda@chaph.usc.edu (Abu Wawda) wrote:

 >After reading the thread on "Good C interview questions", I've got to
 >ask people to post some tricky/trivia questions on programming in C or
 >even programming in general. Does anyone have any? Thanks in advance.

If "tricky/trivia C questions" are being used as a basis of anything in a job
interview, or as a way of "eliminiating" or "approving" job applicants...

...any job applicant should be rightfully offended and walk right out the
door...
 
If someone applies for a job at McDonalds are they tested on how to flip a
burger if they have previous experience?

In any case, for anyone who is thinking of hiring people...and thinking of
"Good C interview questions"... IMO, *DON'T* 

To me, that's akin to handing in a resume' in ALL CAPS.  Rude and trite.  I
wouldn't work someplace that handed me a "test"... 

Dep

In article <4k611a$aln@solutions.solon.com>
           clgonsal@undergrad.math.uwaterloo.ca
           "Carl Laurence Gonsalves" writes:

> >Very little since MAXINT isn't defined. :-) Perhaps if you were to include
> >limits.h and use INT_MAX instead. If you want to add a bit of interest to
> >the problem you could ask the same question about:
> >
> >#include <stddef.h>
> >#include <limits.h>
> >
> >    size_t l;
> >    short i = SHRT_MAX;
> >
> >    l = sizeof(++i);
>
>Whatever the case, one can always say l==sizeof(i) (the actual numerical
>value is implementation dependant),

Right (at least where i is a scalar). Compare that with:

       l = sizeof(+i);

to see the possible pitfall.

>and i remains unchanged from it's
>initial value, whether that's MAXINT, INT_MAX, SHRT_MAX, FOO, 5, etc.

or even uninitialised.

>I think the original poster's point was that the above code does not change
>the value of i, which is not obvious unless you know that sizeof does not
>evaluate it's operand.

No doubt! Some other curious examples are:

       l = sizeof(i/0);
       l = sizeof sizeof i;

       int a[10];
       l = sizeof a[100];
      
-- 
-----------------------------------------
Lawrence Kirby | fred@genesis.demon.co.uk
Wilts, England | 70734.126@compuserve.com
-----------------------------------------

I tend to agree with Dep.

I think I would be more interested in the applicant's design methodology
and how problems are approached in detail. From my perspective, I am 
looking for a fit of my requirements for the job (after all, I got a
project to get out) and how the applicant fits in. Besides, tricky C
is not what I want to see in production code.

I think being cute and tricky during an interview is more for inflating
the ego of the interviewer; and as pointed out; somewhat rude. If the
interviewer is any good, you don't have to resort to tricks to make 
the final judgement.


-- 
Cheers....

Thomas Tempero				Design Acceleration, Inc
tilt@designacc.com			Rochester Design Center
					1530 Highway 52 N, Suite 1076	
					Rochester, MN

In article <4k1pks$514@solutions.solon.com>,
Lawrence Kirby  <fred@genesis.demon.co.uk> wrote:

 >Very little since MAXINT isn't defined. :-) Perhaps if you were to include
 >limits.h and use INT_MAX instead. If you want to add a bit of interest to
 >the problem you could ask the same question about:
 >
 >#include <stddef.h>
 >#include <limits.h>
 >
 >    size_t l;
 >    short i = SHRT_MAX;
 >
 >    l = sizeof(++i);

So what would it be? The result ++i does not undergo intergral promotion. A
better question might be to ask about sizeof(+i), which does force integral
promotion.

This is quite subtle. Both the ++ and the + are defined in the unary-expression
syntactic unit. The only syntactic difference is that the ++ recursively takes
a unary-expression, whereas the + expects a cast-expression.
-- 

In article <4k6187$aoq@solutions.solon.com>, Depeche  <depeche@rtd.com> wrote:
 >wawda@chaph.usc.edu (Abu Wawda) wrote:
 >
 > >After reading the thread on "Good C interview questions", I've got to
 > >ask people to post some tricky/trivia questions on programming in C or
 > >even programming in general. Does anyone have any? Thanks in advance.
 >
 >If "tricky/trivia C questions" are being used as a basis of anything in a job
 >interview, or as a way of "eliminiating" or "approving" job applicants...
 >
 >...any job applicant should be rightfully offended and walk right out the
 >door...
 > 
 >If someone applies for a job at McDonalds are they tested on how to flip a
 >burger if they have previous experience?
 >
 >In any case, for anyone who is thinking of hiring people...and thinking of
 >"Good C interview questions"... IMO, *DON'T* 
 >
 >To me, that's akin to handing in a resume' in ALL CAPS.  Rude and trite.  I
 >wouldn't work someplace that handed me a "test"... 
 >
 >Dep

Cool! That just leaves one more opportunity for someone like me, who wouldn't
mind taking a little test to prove that I know what I'm talking about.

Testing is a good way to separate the wheat from the chaff. All the other
things can be faked: phony references, exaggereated resumes, degree earned by
cheating your way through school or completely faked, etc.
-- 

In article <4jttd2$3iq@solutions.solon.com>,
Greg Shubin <gshubin@wco.com> wrote:
>Here's a little example of C's inconsistent syntax:
>
>int * i, * j, k;
>
>k = *i/*j;

I think that should be:

k = *i/*j*/;

otherwise you have an unterminated comment! ;)
--