c# interview question

[=?Utf-8?B?U3RldmUgQnVnZGVu?=]

Hi,

I recently had an interview where I was asked a number of questions on C#.
Unfortunately I didn't get the answers from the test and find that one of
them is still niggling me.

It was something like this:

Consider the following code:

int i = 0;
Console.WriteLi ne("The value is: " + i);
Console.WriteLi ne("The value is: " + i.ToString());

Which would you use to write an integer to the console and why would it give
better performance?

I said I would use: Console.WriteLi ne("The value is: " +
i.ToString());

But I can't think why this should give a performance advantage. I can only
guess that the compiler should be able to realise that a string is required
from the integer for the line not using the ToString() method and generate
the same MSIL.

Can anyone please enlighten me?

Best Regards,

Steve

[DeveloperX]

On 13 Mar, 16:05, "Mike Schilling" <a...@newsgroup .nospamwrote:

DeveloperX wrote:

time. Just an example.

Oh well as I said, The entire thread went off topic, my original
intention was to show the different operation of the two lines, I
didn't expect to be called an idiot for trying to explain how
something works, so apologies if I came across as overly defensive.

I wasn't calling you an idiot, but the interviewer, for

1. Considering this bit of trivia important, and
2. Expecting the OP to know it off the top of his head.

I disagree with you that there's clearly a performance issue here; there's
no way of telling that without knowing what the JIT output looks like, but I
wouldn't insult you over that.

Ah well that's ok then, sorry for the misunderstandin g, I felt quite
annoyed at the time. I understand the context of your performance
comments and basically agree. In reality I'd be profiling the
application looking for tweaks and bottlenecks as opposed to
disassembling it and pouring over the IL, although there's every
possibility I'd apply such a tiny change if I thought the benefit was
there.

Well, I've picked up some interesting tidbits along the way, so it's
not all lost, so cheers guys and onward :)

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Mike Schilling wrote:

DeveloperX wrote:

>time. Just an example.

Oh well as I said, The entire thread went off topic, my original
intention was to show the different operation of the two lines, I
didn't expect to be called an idiot for trying to explain how
something works, so apologies if I came across as overly defensive.

I wasn't calling you an idiot, but the interviewer

Actually you were clearly referring to the other posters in the thread,
not the interviewer, when you state the criteria for being an idiot.
Claiming that everyone who don't share your opionions are idiots, is not
the best way of entering a debate. I can understand if people get upset
by that.

>, for

1. Considering this bit of trivia important, and

That is only your opinion, and not sharing it is no reason to suspect a
lack of intellectual capacity.

2. Expecting the OP to know it off the top of his head.

I wouldn't expect anyone to know the answers to every question in an
interview. Then the questions are too easy, or the applicant overqualified.

I would however consider the answer that there is no difference between
the lines to be worse than admitting that you don't know the difference.

I disagree with you that there's clearly a performance issue here;

The given code clearly has no performance problems, but it demonstrates
boxing, which clearly can cause performance problems.

there's
no way of telling that without knowing what the JIT output looks like,

Sure there is. Examining the IL code works just as well.

but I
wouldn't insult you over that.

--
Göran Andersson
_____
http://www.guffa.com

[PFC Sadr]

Q) Do you use C#
A) Don't hire anyone that says YES; because VB is an obviously
superior langauge with greater code portability

On Mar 12, 2:39 am, Steve Bugden
<SteveBug...@di scussions.micro soft.comwrote:

Hi,

I recently had an interview where I was asked a number of questions on C#.
Unfortunately I didn't get the answers from the test and find that one of
them is still niggling me.

It was something like this:

Consider the following code:

int i = 0;
Console.WriteLi ne("The value is: " + i);
Console.WriteLi ne("The value is: " + i.ToString());

Which would you use to write an integer to the console and why would it give
better performance?

I said I would use: Console.WriteLi ne("The value is: " +
i.ToString());

But I can't think why this should give a performance advantage. I can only
guess that the compiler should be able to realise that a string is required
from the integer for the line not using the ToString() method and generate
the same MSIL.

Can anyone please enlighten me?

Best Regards,

Steve

[Nitin Sharma]

int i = 0;
//This will use implicit conversion
Console.WriteLi ne("The value is: " + i);
//This will not use implcit conversion as we already declared ToString()
so Performance will be fast.
Console.WriteLi ne("The value is: " + i.ToString());
Console.Read();

Nitin Sharma
(Guru .Net)

*** Sent via Developersdex http://www.developersdex.com ***

[Brian Gideon]

On Mar 14, 7:13 am, Nitin Sharma <loinni...@gmai l.comwrote:

int i = 0;
//This will use implicit conversion
Console.WriteLi ne("The value is: " + i);
//This will not use implcit conversion as we already declared ToString()
so Performance will be fast.
Console.WriteLi ne("The value is: " + i.ToString());
Console.Read();

Nitin Sharma
(Guru .Net)

*** Sent via Developersdexht tp://www.developersd ex.com***

There is no implicit conversion from int to string. I just checked
the C# specification to make sure. DeveloperX already explained why
the later is faster several posts up. Also, as written, the
performance of those two lines is nearly identical.