What type of questions can be asked in an technical interview of C

[Cherrish Vaidiyan]

Frinds,

Hope everyone is doing fine.i feel pointers to be the most toughest
part in C. i have just completed learning pointers & arrays related
portions. I need to attend technical interview on C. wat type of
questions should be expected? Which part of C language do the staff
give more concern?
The interviewers have just mentioned that .. i will have interview on
C.
Also can anyone can help me with sites where i can go thru sample
programs in C?

Thanking you all...
Cherry

[Joona I Palaste]

Cherrish Vaidiyan <un************ ***@yahoo.com> scribbled the following:

Frinds, Hope everyone is doing fine.i feel pointers to be the most toughest
part in C. i have just completed learning pointers & arrays related
portions. I need to attend technical interview on C. wat type of
questions should be expected? Which part of C language do the staff
give more concern?
The interviewers have just mentioned that .. i will have interview on
C.
Also can anyone can help me with sites where i can go thru sample
programs in C?

This is impossible to answer specifically, as it would require reading
the company's mind. But I think you're off to a good start with pointers
and arrays. Other topics that can come up are functions (calling and
parameter passing mechanisms), the type system, and preprocessor macros.
The most important rule I can think of is to learn the core language
first, and any possible OS-specific APIs second, if at all. Knowing
which flag to set to make the X widget turn purple is of no use if you
don't know how function calls work.

--
/-- Joona Palaste (pa*****@cc.hel sinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"This is a personnel commuter."
- Train driver in Scientific American

[Malcolm]

"Cherrish Vaidiyan" <un************ ***@yahoo.com> wrote in

I need to attend technical interview on C. wat type of
questions should be expected?

See if you can answer these.

What is wrong with

1)
#define min(x, y) x < y ? x : y

2)
char str[5] = "Hello";

3)

for(i=0;i<strle n(str);i++)
if(str[i] == 'a')
answer++;

4)
if( ch != '.' || ch != ',')

5)
char *foo(int x)
{
char buff[32];
sprintf(buff, "%d", x);
return buff;
}

[Joona I Palaste]

Malcolm <ma*****@55bank .freeserve.co.u k> scribbled the following:

"Cherrish Vaidiyan" <un************ ***@yahoo.com> wrote in

I need to attend technical interview on C. wat type of
questions should be expected?
See if you can answer these.

What is wrong with 3) for(i=0;i<strle n(str);i++)
if(str[i] == 'a')
answer++;

Am I blind or something? Other than doing more work than necessary (and
such slowing the program down) I can find nothing wrong with this.

--
/-- Joona Palaste (pa*****@cc.hel sinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"'I' is the most beautiful word in the world."
- John Nordberg

[Malcolm]

"Joona I Palaste" <pa*****@cc.hel sinki.fi> wrote in message

What is wrong with

3)

for(i=0;i<strle n(str);i++)
if(str[i] == 'a')
answer++;

Am I blind or something? Other than doing more work than necessary (and
such slowing the program down) I can find nothing wrong with this.

It shows a rather different problem to the others. Hint, what happens if str
is a very long string?

[Thomas Stegen]

Joona I Palaste wrote:

3)

for(i=0;i<str len(str);i++)
if(str[i] == 'a')
answer++;

Am I blind or something? Other than doing more work than necessary (and
such slowing the program down) I can find nothing wrong with this.

It is not wrong as such. Problem is that it is in Omega(n^2).
It is a Nilgesqian problem in other words.

--
Thomas.

[code_wrong]

"Malcolm" <ma*****@55bank .freeserve.co.u k> wrote in message
news:c4******** **@news6.svr.po l.co.uk...

"Cherrish Vaidiyan" <un************ ***@yahoo.com> wrote in

I need to attend technical interview on C. wat type of
questions should be expected?
See if you can answer these.

What is wrong with

1)
#define min(x, y) x < y ? x : y

if x == y it returns y anyway?
2)
char str[5] = "Hello";
no space for string terminating null character
3)

for(i=0;i<strle n(str);i++)
if(str[i] == 'a')
answer++;
pass
4)
if( ch != '.' || ch != ',')
always evaluates to false
5)
char *foo(int x)
{
char buff[32];
sprintf(buff, "%d", x);
return buff;
}

returns pointer to local variable which will be destroyed
when the function has finished executing and will not be.

Where can I find more of these?
solutions will be useful.
cheers
cw

[Thomas Stegen]

code_wrong wrote:

"Malcolm" <ma*****@55bank .freeserve.co.u k> wrote in message
news:c4******** **@news6.svr.po l.co.uk...

"Cherrish Vaidiyan" <un************ ***@yahoo.com> wrote in

I need to attend technical interview on C. wat type of
questions should be expected?

See if you can answer these.

What is wrong with

1)
#define min(x, y) x < y ? x : y

if x == y it returns y anyway?

x == y returns 1 or 0. Need some brackets.

#define min(x, y) ((x) < (y) ? (x) : (y))

2)
char str[5] = "Hello";

no space for string terminating null character

Correct. But that is not always an error. But if it is not a mistake
I would imagine a comment being a very very good idea.

3)

for(i=0;i<str len(str);i++)
if(str[i] == 'a')
answer++;
pass

On every iteration strlen is called. (Yoda speak to avoid starting
a sentence with a function name is always fun). The loop is in
Omega(n^2) instead of Omega(n) where it should be. But it is perfectly
valid C.

4)
if( ch != '.' || ch != ',')

always evaluates to false

Umm, I think you got that the wrong way around?
Just think that ch can never be equal to two things at the
same time.

5)
char *foo(int x)
{
char buff[32];
sprintf(buff, "%d", x);
return buff;
}

returns pointer to local variable which will be destroyed
when the function has finished executing and will not be.

It will not be... A nice turn of phrase, but otherwise correct :)

--
Thomas.

[CBFalconer]

Malcolm wrote:

"Joona I Palaste" <pa*****@cc.hel sinki.fi> wrote in message

What is wrong with

3)

for(i=0;i<strle n(str);i++)
if(str[i] == 'a')
answer++;

Am I blind or something? Other than doing more work than
necessary (and such slowing the program down) I can find
nothing wrong with this.

It shows a rather different problem to the others. Hint, what
happens if str is a very long string?

It keeps the CPU out of mischief. Still nothing _wrong_ with it.

--
Chuck F (cb********@yah oo.com) (cb********@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!

[William L. Bahn]

"Malcolm" <ma*****@55bank .freeserve.co.u k> wrote in message
news:c4******** **@news6.svr.po l.co.uk...

"Cherrish Vaidiyan" <un************ ***@yahoo.com> wrote in

I need to attend technical interview on C. wat type of
questions should be expected?
See if you can answer these.

What is wrong with

1)
#define min(x, y) x < y ? x : y

Does not protect against unwanted precedence evaluations. Should be:

#define min(x, y) ( ((x) < (y)) ? (x) : (y) )

I have an extra pair of parens around the logical expression - just part of
my preferred style.

2)
char str[5] = "Hello";
To store "Hello" as a string requires a 6th byte for the terminating null.
Don't know off the top of my head if the compiler will automatically expand
the definition - since it has all the information it needs - or not.

3)

for(i=0;i<strle n(str);i++)
if(str[i] == 'a')
answer++;
Calling strlen() each pass is highly inefficient, but not "wrong". I would
also recommend reversing the operands in the if() statment:

if('a' == str[i])

that way if you goof and make the common mistake of typing '=' instead of
'==' you have just turned a logic error that might be a royal pain to track
down into a syntax error that the compiler will catch immediately.

4)
if( ch != '.' || ch != ',')
Almost certainly a logic error as it will always evaluate as true. Probably
meant to be && operator.

5)
char *foo(int x)
{
char buff[32];
sprintf(buff, "%d", x);
return buff;
}
buff is an automatic variable that is deallocated after foo() finishes
execution.