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# Programming Puzzle

I found these questions on a web site and wish to share with all of u
out there,Can SomeOne Solve these Porgramming puzzles.
Programming Puzzles

Some companies certainly ask for these things. Specially Microsoft.
Here are my favorite puzzles. Don't send me emails asking for the
solutions.

Q1 Write a "Hello World" program in 'C' without using a semicolon.
Q2 Write a C++ program without using any loop (if, for, while etc) to
print numbers from 1 to 100 and 100 to 1;
Q3 C/C++ : Exchange two numbers without using a temporary variable.
Q4 C/C++ : Find if the given number is a power of 2.
Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator.
Q6 C/C++ : Write a function in different ways that will return f(7) =
4 and f(4) = 7
Q7 Remove duplicates in array
Q8 Finding if there is any loop inside linked list.
Q9 Remove duplicates in an no key access database without using an
array
Q10 Write a program whose printed output is an exact copy of the
source. Needless to say, merely echoing the actual source file is not
allowed.
Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's),
each player selects a number and adds it to the total. Once a number
is used, it must be removed from the pool. The winner is the person
whose number makes the total equal 31 exactly.
Q12 Swap two numbers without using a third variable.
Given an array (group) of numbers write all the possible sub groups of
this group.
Q14 Convert (integer) number in binary without loops.

Q3,12 are similar , Q7 is simple & I know there answer For the Rest
Nov 14 '05
271 20382
Alex Monjushko wrote:
Not necessarily. Consider the following, in the same translation unit.

static int a = 42;

extern int a; /* deceptive use of 'extern' */

As I had said for this one later in the message:

"extern int k; means that it is defined elsewhere (in general)"

Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys
Nov 14 '05 #261
In comp.lang.c Ioannis Vranos <iv*@guesswh.at .grad.com> wrote:
Alex Monjushko wrote:
Not necessarily. Consider the following, in the same translation unit.

static int a = 42;

extern int a; /* deceptive use of 'extern' */

As I had said for this one later in the message: "extern int k; means that it is defined elsewhere (in general)"

"Elsewhere" is technically correct, but it is a little vague in light
of your initial reference to separate translation units.

--
Alex Monjushko (mo*******@hotm ail.com)
Nov 14 '05 #262
Alex Monjushko wrote:
In comp.lang.c Ioannis Vranos <iv*@guesswh.at .grad.com> wrote:
Alex Monjushko wrote:

Not necessarily. Consider the following, in the same translation unit.

static int a = 42;

extern int a; /* deceptive use of 'extern' */

As I had said for this one later in the message:

"extern int k; means that it is defined elsewhere (in general)"

"Elsewhere" is technically correct, but it is a little vague in light
of your initial reference to separate translation units.

Ok, OK! :-)

Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys
Nov 14 '05 #263
Keith Thompson wrote:

This is posted only to comp.lang.c++, which I don't regularly follow.

Julie <ju***@nospam.c om> writes:
Ioannis Vranos wrote: [...]
The C++ standard says: [...] "A variable is introduced by the declaration of an object. The
variable's name denotes the object."

Fine -- but what that is saying is that when you create an object, you also
introduce a variable. The opposite is not necessarily true: introducing a
variable does *NOT* imply the declaration of an object.

The first occurence of "variable" in the above quotation from the
standard is in italics. That means it's the definition of the word
"variable", which implies that it's exclusive, i.e., that anything not
introduced by the declaration of an object is not a variable.

You may want to research predicate logic.
That may or may not match the common usage of the term, but if that's
what the standard says it seems appropriate to stick to that
definition.

(The C standard, on the other hand, doesn't define the word
"variable", which is why I dropped comp.lang.c from the Newsgroups

Again, this discussion doesn't have to limit itself to what is or is not
included in any standard. This discussion is about languages, in a forum about
languages (comp.lang.c*), as defined about standards. Variable discussions in
comp.std.c may be inappropriate, here in comp.lang.c, it is perfectly
Nov 14 '05 #264
Ioannis Vranos wrote:
Alex Monjushko wrote:
In comp.lang.c Ioannis Vranos <iv*@guesswh.at .grad.com> wrote:
Alex Monjushko wrote:

Not necessarily. Consider the following, in the same translation unit.

static int a = 42;
extern int a; /* deceptive use of 'extern' */

As I had said for this one later in the message:

"extern int k; means that it is defined elsewhere (in general)"

"Elsewhere" is technically correct, but it is a little vague in light
of your initial reference to separate translation units.

Ok, OK! :-)

Also extern int k; can be a definition by itself in the absence of any
other definition.

Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys
Nov 14 '05 #265
Julie wrote:
Again, this discussion doesn't have to limit itself to what is or is not
included in any standard. This discussion is about languages, in a forum about
languages (comp.lang.c*), as defined about standards. Variable discussions in
comp.std.c may be inappropriate, here in comp.lang.c, it is perfectly

Yes it is about the language as defined by the standard, so we should be
better stick to the terminology of the standard, if for not other reason
to be able to understand one another.

clc on the other hand is another language so by adding other languages
newsgroups can only add more confusion.

Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys
Nov 14 '05 #266
Ioannis Vranos wrote:
Yes it is about the language as defined by the standard, so we should be
better stick to the terminology of the standard, if for not other reason
to be able to understand one another.

clc on the other hand is another language

newsgroup

newsgroups can only add more confusion.

Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys
Nov 14 '05 #267
Ioannis Vranos wrote:

Julie wrote:
"A variable is introduced by the declaration of an object. The
variable’s name denotes the object."

Fine -- but what that is saying is that when you create an object, you also
introduce a variable. The opposite is not necessarily true: introducing a
variable does *NOT* imply the declaration of an object.

No it says that you declare an object by using a variable. So when you
"declare" a variable in essence you declare an object.

It doesn't say that or infer that at all. Research predicate logic. You can't
assume the reverse of an inference is true.

Specifically:

'declaration of an object' implies 'variable is introduced' (always true)

cannot be reversed to:

'variable is introduced' implies 'declaration of an object' (conditionally
true)
If that is the extent of what is discussed in the standard, then the short of
it is that the standard does not define what a variable is.

It does. A variable (its name) denotes an object.
"An object is a region of storage. [Note: A function is not an object,
regardless of whether or not it occupies storage in the way that objects
do. ] An object is created by a definition (3.1), by a new-expression
(5.3.4) or by the implementation (12.2) when needed."

Seems like it isn't complete to me. Either the other ways (C-style?) to
instanciate an 'object' are either implied or just plain left out. Consider
the differences between:

int i; // created by a definition

int * j = new int; // by a new-expression

extern int k; // by the implementation

Actually defined in another compilation unit.

So what? I was giving an example of the something 'created ... by the
implementation' , presuming that k is part of the implementation.
int * l = (int *)malloc(sizeof (int)); // what about me?

In the above cases we have:

int i;

i is a variable that denotes an object.

int *j=new int;

j is a variable that denotes an int * object, that is the pointer itself.

The new int that is created in the free store is another object, not
denoted by a variable, since it is not created by a variable declaration.

extern int k; means that it is defined elsewhere (in general) and the
"int i" case applies for the definition.

The malloc() situation is the same with the new int situation.

Not the same, but similar, and *not* included in the standard text that you
quoted. That was my point -- the standard text is incomplete, or your
quote/reference is.
Nov 14 '05 #268
Julie wrote:
It doesn't say that or infer that at all. Research predicate logic. You can't
assume the reverse of an inference is true.

Specifically:

'declaration of an object' implies 'variable is introduced' (always true)

cannot be reversed to:

'variable is introduced' implies 'declaration of an object' (conditionally
true)

Ok. You may continue wasting your energy in endless discussions. :-)

The malloc() situation is the same with the new int situation.

Not the same, but similar, and *not* included in the standard text that you
quoted. That was my point -- the standard text is incomplete, or your
quote/reference is.

What do you mean not included. It is the same case with operator new.

Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys
Nov 14 '05 #269
Ioannis Vranos wrote:

Julie wrote:
It doesn't say that or infer that at all. Research predicate logic. You can't
assume the reverse of an inference is true.

Specifically:

'declaration of an object' implies 'variable is introduced' (always true)

cannot be reversed to:

'variable is introduced' implies 'declaration of an object' (conditionally
true)

Ok. You may continue wasting your energy in endless discussions. :-)

I'm getting close to being out of energy on this discussion...
Nov 14 '05 #270

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