reverse the bits in an interger?

[KG]

Could any one tell me how to reverse the bits in an interger?

[Joachim Schmitz]

<bo******@gmail .comschrieb im Newsbeitrag
news:11******** **************@ k79g2000hse.goo glegroups.com.. .

On Jun 20, 11:56 am, "Joachim Schmitz" <nospam.j...@sc hmitz-
digital.dewrote :

int reverse_bits(in t n)
{
return ~n;
}

That's inverting (1 turn into 0 and vice versa), not reverting. I
understood
the OP wants the laest significant bit being the most significate, the
2nd
least being the second most and so on.

I did not understand that: the OP asked for to "reverse the bits in an
interger". This function reverses all bits in the integer. What you
are proposing is reversing the order of the bits, which is different.

Apparently (looking at the other answers in this thread) only you and
Richard understood it that way.
My point is that inverting (see
http://en.wikipedia.org/wiki/Inverse_%28logic%29) is not the same as
reverting.

Bye, Jojo

[Richard Heathfield]

Joachim Schmitz said:

<bo******@gmail .comschrieb im Newsbeitrag
news:11******** **************@ k79g2000hse.goo glegroups.com.. .

>On Jun 20, 11:56 am, "Joachim Schmitz" <nospam.j...@sc hmitz-
digital.dewrot e:

>int reverse_bits(in t n)
{
return ~n;
}

That's inverting (1 turn into 0 and vice versa), not reverting. I
understood
the OP wants the laest significant bit being the most significate,
the 2nd
least being the second most and so on.

I did not understand that: the OP asked for to "reverse the bits in
an interger". This function reverses all bits in the integer. What
you are proposing is reversing the order of the bits, which is
different.

Apparently (looking at the other answers in this thread) only you and
Richard understood it that way.

Nevertheless, it demonstrates that the specification was inadequate.
Over 28% of the respondents who had expressed an interpretation at the
time of writing have chosen to interpret "reverse the bits in an
integer" as "reverse the bits in an integer" rather than "reverse the
order of the bits in an integer".

My point is that inverting (see
http://en.wikipedia.org/wiki/Inverse_%28logic%29) is not the same as
reverting.

And reverting is not the same as reversing. And reversing is not the
same as reversing the order.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

[osmium]

<bo******@gmail .comwrote:

On Jun 20, 11:56 am, "Joachim Schmitz" <nospam.j...@sc hmitz-
digital.dewrote :

int reverse_bits(in t n)
{
return ~n;
}

That's inverting (1 turn into 0 and vice versa), not reverting. I
understood
the OP wants the laest significant bit being the most significate, the
2nd
least being the second most and so on.

I did not understand that: the OP asked for to "reverse the bits in an
interger". This function reverses all bits in the integer. What you
are proposing is reversing the order of the bits, which is different.

Most people whose natural language is English would say "invert the *sense*
of the bits", for what you are describing.

[Army1987]

"Richard Heathfield" <rj*@see.sig.in validha scritto nel messaggio news:Wt******** *************** *******@bt.com. ..

Joachim Schmitz said:

><bo******@gmai l.comschrieb im Newsbeitrag
news:11******* *************** @k79g2000hse.go oglegroups.com. ..

>>On Jun 20, 11:56 am, "Joachim Schmitz" <nospam.j...@sc hmitz-
digital.dewro te:
int reverse_bits(in t n)
{
return ~n;
}

That's inverting (1 turn into 0 and vice versa), not reverting. I
understood
the OP wants the laest significant bit being the most significate,
the 2nd
least being the second most and so on.

I did not understand that: the OP asked for to "reverse the bits in
an interger". This function reverses all bits in the integer. What
you are proposing is reversing the order of the bits, which is
different.

Apparently (looking at the other answers in this thread) only you and
Richard understood it that way.

Nevertheless, it demonstrates that the specification was inadequate.
Over 28% of the respondents who had expressed an interpretation at the
time of writing have chosen to interpret "reverse the bits in an
integer" as "reverse the bits in an integer" rather than "reverse the
order of the bits in an integer".

>My point is that inverting (see
http://en.wikipedia.org/wiki/Inverse_%28logic%29) is not the same as
reverting.

And reverting is not the same as reversing. And reversing is not the
same as reversing the order.

http://dictionary.reference.com/browse/reverse
Yes, it is not 100% clear, but the most likely meaning is reversing
the order. (Anyway, since correct answers to both the meanings of
the question have been giving, arguing on which one was meant,
until the OP tells us, is sort-of waste of time.)

[Joachim Schmitz]

"Richard Heathfield" <rj*@see.sig.in validschrieb im Newsbeitrag
news:Wt******** *************** *******@bt.com. ..

Joachim Schmitz said:

><bo******@gmai l.comschrieb im Newsbeitrag
news:11******* *************** @k79g2000hse.go oglegroups.com. ..

>>On Jun 20, 11:56 am, "Joachim Schmitz" <nospam.j...@sc hmitz-
digital.dewro te:
int reverse_bits(in t n)
{
return ~n;
}

That's inverting (1 turn into 0 and vice versa), not reverting. I
understood
the OP wants the laest significant bit being the most significate,
the 2nd
least being the second most and so on.

I did not understand that: the OP asked for to "reverse the bits in
an interger". This function reverses all bits in the integer. What
you are proposing is reversing the order of the bits, which is
different.

Apparently (looking at the other answers in this thread) only you and
Richard understood it that way.

Nevertheless, it demonstrates that the specification was inadequate.

True, incomplete and leaves room for interpretation.

Over 28% of the respondents who had expressed an interpretation at the
time of writing have chosen to interpret "reverse the bits in an
integer" as "reverse the bits in an integer"

"invers the bits in an integer". (or "invert"?) A bit that is set when read
left to right is still set when read right to left, so revers wouldn't be
the right word. But hell, this isn't my native language...

rather than "reverse the order of the bits in an integer".

That could indeed have been the full specification.
Time for the OP to show up and confirm.

>My point is that inverting (see
http://en.wikipedia.org/wiki/Inverse_%28logic%29) is not the same as
reverting.

And reverting is not the same as reversing.

Oops, of course I meant reversing as the OP wrote.

And reversing is not the same as reversing the order.

What else? To me it is the same. What would 'reverse a string' be to you?
Turn the characters upside down? 8-)

Bye, Jojo

[Richard Heathfield]

Army1987 said:

>
"Richard Heathfield" <rj*@see.sig.in validha scritto nel messaggio
news:Wt******** *************** *******@bt.com. ..

>Joachim Schmitz said:

<snip>

>>My point is that inverting (see
http://en.wikipedia.org/wiki/Inverse_%28logic%29) is not the same as
reverting.

And reverting is not the same as reversing. And reversing is not the
same as reversing the order.

http://dictionary.reference.com/browse/reverse
Yes, it is not 100% clear, but the most likely meaning is reversing
the order.

To your mind, maybe. But it makes much more sense to write the
specification in a way that makes the requirement clear, right from the
start, to *everybody*.

(Anyway, since correct answers to both the meanings of
the question have been giving, arguing on which one was meant,
until the OP tells us, is sort-of waste of time.)

I am not, and have not been, arguing about which one the OP meant. I am
arguing that a clear specification is a sine qua non of a correct
program.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

[Chris Dollin]

osmium wrote:

<bo******@gmail .comwrote:

>On Jun 20, 11:56 am, "Joachim Schmitz" <nospam.j...@sc hmitz-
digital.dewrot e:

>int reverse_bits(in t n)
{
return ~n;
}

That's inverting (1 turn into 0 and vice versa), not reverting. I
understood
the OP wants the laest significant bit being the most significate, the
2nd
least being the second most and so on.

I did not understand that: the OP asked for to "reverse the bits in an
interger". This function reverses all bits in the integer. What you
are proposing is reversing the order of the bits, which is different.

Most people whose natural language is English would say "invert the *sense*
of the bits", for what you are describing.

I'm not most people [1], but I think you're wrong.
For those with any interest in the matter at all,
I think they'd say "invert the bits", with
no nonsense about "sense". Or they'd use "flip".
Or "reverse". Or "complement ".

I rather suspect that the OP meant "reverse
the order of the bits", but experience in
support on another mailing list suggests that
users asking about something different from
what they /say/ they're asking about
happens often enough that mere suspecting
doesn't bake the biscuit.

[1] For which we're all grateful.

--
Hewlett-Packard Limited Cain Road, Bracknell, registered no:
registered office: Berks RG12 1HN 690597 England

[Richard Heathfield]

Joachim Schmitz said:

"Richard Heathfield" <rj*@see.sig.in validschrieb im Newsbeitrag
news:Wt******** *************** *******@bt.com. ..

<snip>

>And reversing is not the same as reversing the order.

What else? To me it is the same. What would 'reverse a string' be to
you? Turn the characters upside down? 8-)

It could reasonably be interpreted as ROT-((UCHAR_MAX + 1)/2).

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

[CBFalconer]

Anonymous wrote:

On Jun 20, 2:40 pm, KG <Kriti.Goyal.t. [e-mail] te:

>Could any one tell me how to reverse the bits in an interger?

First of all you need to know the size of integer, then you should
go somthing like this:

Well, in all this nonsense I have seen nothing that actually
reverses the order of bits in an unsigned int, independent of
sizeof int. So try this:

while (i) {
push(i & 1, stack);
i >>= 1;
}
while (notempty(stack )) {
i <<= 1;
j = pop(stack);
i != j;
}

with suitable declarations, stack, etc.

--
<http://www.cs.auckland .ac.nz/~pgut001/pubs/vista_cost.txt>
<http://www.securityfoc us.com/columnists/423>
<http://www.aaxnet.com/editor/edit043.html>
cbfalconer at maineline dot net

--
Posted via a free Usenet account from http://www.teranews.com

[Richard Harter]

On Wed, 20 Jun 2007 10:55:40 -0400, CBFalconer <cb********@yah oo.com>
wrote:

>Anonymous wrote:

>On Jun 20, 2:40 pm, KG <Kriti.Goyal.t. [e-mail] te:

>>Could any one tell me how to reverse the bits in an interger?

First of all you need to know the size of integer, then you should
go somthing like this:

Well, in all this nonsense I have seen nothing that actually
reverses the order of bits in an unsigned int, independent of
sizeof int. So try this:

while (i) {
push(i & 1, stack);
i >>= 1;
}
while (notempty(stack )) {
i <<= 1;
j = pop(stack);
i != j;
}

with suitable declarations, stack, etc.

You have just exposed a second and much more serious ambiguity, to wit,
what precisely is meant by integer and how is it delimited. The issue is
what determines the number of leading zeroes and the length of the answer.
To illustrate suppose that our "integer" is 00110001 (8 bit words). Is the
correct answer 10001100 or 100011 or 00100011?