Hi,
What will happen in following scenario..
long a = -2;
longlong b = a
long c;
c = *(ulonglong *)&b;
b = c;
also when
long d;
d = *&b;
b = d;
What will be the value of b ? When will it lose the upper 32bits ?
regards
amit
Nov 14 '05
25  2687 
In <r2************ *************** *****@4ax.com> Leor Zolman <le**@bdsoft.co m> writes: On Wed, 07 Apr 2004 01:13:59 GMT, Leor Zolman <le**@bdsoft.co m> wrote:
Well, that was my very first time attempting to display values of long
longs, and in my confusion I ended up with a spurious "d" in four format
conversions (I put %uld when %ul was sufficient for a plain unsigned long).
Bzzzt, still wrong. The *correct* conversion descriptor for unsigned long
is, and has always been, %lu. %ul expects an unsigned int and appends an
'l' to its value. If it receives an unsigned long, undefined behaviour.
Fortunately, that didn't really break the output, except that there's a
trailing, meaningless 'd' at the end of 4 of the lines. Sorry about that.
It broke everything, due to invoking undefined behaviour, so any output
you got was by accident, rather than by design.
P.S. It took me a while to find a platform that displayed long long values
at all! Good thing I had that Dinkum lib lying around... ;-)
It's been a common Unix extension for ages...
Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
On 7 Apr 2004 14:09:27 GMT, Da*****@cern.ch (Dan Pop) wrote: In <r2************ *************** *****@4ax.com> Leor Zolman <le**@bdsoft.co m> writes:
On Wed, 07 Apr 2004 01:13:59 GMT, Leor Zolman <le**@bdsoft.co m> wrote:
Well, that was my very first time attempting to display values of long
longs, and in my confusion I ended up with a spurious "d" in four format
conversions (I put %uld when %ul was sufficient for a plain unsigned long).
Bzzzt, still wrong. The *correct* conversion descriptor for unsigned long
is, and has always been, %lu. %ul expects an unsigned int and appends an
'l' to its value. If it receives an unsigned long, undefined behaviour.
I guess at least technically, I don't need to say "I spoke too soon" :-)
Fortunately , that didn't really break the output, except that there's a
trailing, meaningless 'd' at the end of 4 of the lines. Sorry about that.
It broke everything, due to invoking undefined behaviour, so any output
you got was by accident, rather than by design.
P.S. It took me a while to find a platform that displayed long long values
at all! Good thing I had that Dinkum lib lying around... ;-)
It's been a common Unix extension for ages...
I only use Unix for teaching Unix and making tar files (and for the
latter, Cgwin actually...)
-leor
--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at: www.bdsoft.com/tools/stlfilt.html
On 7 Apr 2004 14:09:27 GMT, Da*****@cern.ch (Dan Pop) wrote: In <r2************ *************** *****@4ax.com> Leor Zolman <le**@bdsoft.co m> writes:
On Wed, 07 Apr 2004 01:13:59 GMT, Leor Zolman <le**@bdsoft.co m> wrote:
Well, that was my very first time attempting to display values of long
longs, and in my confusion I ended up with a spurious "d" in four format
conversions (I put %uld when %ul was sufficient for a plain unsigned long).
Bzzzt, still wrong. The *correct* conversion descriptor for unsigned long
is, and has always been, %lu. %ul expects an unsigned int and appends an
'l' to its value. If it receives an unsigned long, undefined behaviour.
I guess at least technically, I don't need to say "I spoke too soon" :-)
Fortunately , that didn't really break the output, except that there's a
trailing, meaningless 'd' at the end of 4 of the lines. Sorry about that.
It broke everything, due to invoking undefined behaviour, so any output
you got was by accident, rather than by design.
P.S. It took me a while to find a platform that displayed long long values
at all! Good thing I had that Dinkum lib lying around... ;-)
It's been a common Unix extension for ages...
I only use Unix for teaching Unix and making tar files (and for the
latter, Cgwin actually...)
-leor
--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at: www.bdsoft.com/tools/stlfilt.html
Leor Zolman wrote:
.... snip ...
I only use Unix for teaching Unix and making tar files (and for
the latter, Cgwin actually...)
Try DJGPP. Much faster. Does all those things.
--
Some useful references:
<http://www.ungerhu.com/jxh/clc.welcome.txt >
<http://www.eskimo.com/~scs/C-faq/top.html>
<http://benpfaff.org/writings/clc/off-topic.html>
On Wed, 07 Apr 2004 22:12:53 GMT, CBFalconer <cb********@yah oo.com> wrote: Leor Zolman wrote:
... snip ...
I only use Unix for teaching Unix and making tar files (and for
the latter, Cgwin actually...)
Try DJGPP. Much faster. Does all those things.
Oh, I have that here. Not sure I ever realized it does C. I got the gcc
version of STLFilt (for C++ of course) supporting djgpp back in 2002...and
I just realized that nowhere in my docs is that fact actually documented.
That's because I just think of djgpp as "yet another gcc clone", and
figured everyone else would probably know that its messages would be the
same as those of "vanilla" gcc. Foo. Thanks for the heads up!
-leor
--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at: www.bdsoft.com/tools/stlfilt.html
In <kc************ *************** *****@4ax.com> Leor Zolman <le**@bdsoft.co m> writes: On 7 Apr 2004 14:09:27 GMT, Da*****@cern.ch (Dan Pop) wrote:
In <r2************ *************** *****@4ax.com> Leor Zolman <le**@bdsoft.co m> writes:
P.S. It took me a while to find a platform that displayed long long values
at all! Good thing I had that Dinkum lib lying around... ;-)
It's been a common Unix extension for ages...
I only use Unix for teaching Unix and making tar files (and for the
latter, Cgwin actually...)
^^^^^^^^^^^^^^
Cygwin's gcc and libraries have supported long long forever, so you had
such a platform right under your nose ;-)
Dan
--
Dan Pop
DESY Zeuthen, RZ group
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