bitset

bitset

[Rudra Banerjee]

Dear friends, 
i am in mess with bitset again. i have managed to write a messy code 
which checks the machine bitsize and then wants to do a bitflip. here 
is the code: 
int bit; 
if (strncmp(sysptr, "i686",4)==0) 
{ 
bit=32; 

} 

...... 
bitset<32> i (0); 
....etc. 
where in bitset is equal to bit,which is 32. but i tried to write the 
bitset as *bitset<bit> i (0);*(i.e. to read the bit as an integer variable) 
where its giving the error:error: ‘bit’ cannot appear in a constant- expression 
can you tell me a way to make that possible? 
 
-- 
Rudra
JRF; SNBNCBS
http://www.bose.res.in/~rudra

A bus station is where a bus stops. A train station is where a train
stops. On my desk I have a work  station.

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----- Original Message ----
From: "gcc-help-digest-help@gcc.gnu.org" <gcc-help-digest-help@gcc.gnu.org>
To: gcc-help@gcc.gnu.org
Sent: Thursday, 10 July, 2008 4:00:09 AM
Subject: gcc-help Digest 9 Jul 2008 22:30:09 -0000 Issue 2773


gcc-help Digest 9 Jul 2008 22:30:09 -0000 Issue 2773

Topics (messages 33368 through 33386):

directory separators in compiler generated assembly code
    33368 by: Brian Dessent <brian@dessent.net>
    33379 by: "Joe Tilton" <jhtilton@gmail.com>

Including <iostream> affects whether or not program freezes?
    33369 by: "James Gregory" <james.jrg@gmail.com>
    33372 by: Lionel B <lionelb.nospam@gmail.com>
    33375 by: "Andrew Bell" <andrew.bell.ia@gmail.com>
    33376 by: Andrew Haley <aph@redhat.com>
    33380 by: "James Gregory" <james.jrg@gmail.com>
    33381 by: "Chris Jefferson" <chris@bubblescope.net>
    33382 by: Burlen Loring <burlen..loring@kitware.com>

rambling about cross build inefficiencies, unclarities, and  pie-in-the-sky
    33370 by: Jay <jayk123@hotmail.com>

bitset in C
    33371 by: Rudra Banerjee <bnrj.rudra@yahoo.com>
    33383 by: Dan Hipschman <dsh@linux.ucla.edu>

gcc for AIX
    33373 by: "Vardhan, Sundara (GE Infra, Energy)" <sundara.vardhan@ge.com>
    33374 by: "Eric Fernandez" <efernandez@physiomics-plc.com>

Passing information from analysis pass to assembly code
    33377 by: Timothy M Jones <tjones1@inf.ed.ac.uk>

Little Endian vs Big Endian
    33378 by: "Vardhan, Sundara (GE Infra, Energy)" <sundara.vardhan@ge.com>

Gcc 4.3.1 installed , butproblem is with the asseembler
    33384 by: gcc_help <pganesh@moris.org>

questions about gcc PIC port
    33385 by: Platone Ilia <plato@uruzuki.com>

GCC-4.3.1 source from mirror - no configure file
    33386 by: "Ellis Robin (Bundaberg)" <Robin.Ellis@nrw.qld.gov.au>

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----------------------------------------------------------------------
Hi list, I just downloaded the gcc-4.3.1 source (gcc-4.3.1.tar.gz) from
an ftp in Japan (ftp://ftp.dti.ad.jp/pub/lang/gcc/releases/gcc-4.3.1)
and have attempted to configure from my build directory on solaris 10,
only to find that I don't have a 'configure' file in my source. Is this
just a temporary glitch, or has the configuration requirements changed
since early February?

Thanks

Rob

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RE: bitset

[Rupert Wood]

Rudra Banerjee wrote:

> bitset<bit> i (0);*(i.e. to read the bit as an integer variable)

No, what you're actually saying there is "define i as a bitset container for 'bit' bits". Since 'bit' can vary at runtime the compiler won't let you do this.

I don't know bitsets but looking at the docs to access bit x of a bitset container b you can use:

    b.test(x)

To test bit x of an integer i without using bitsets you can use:

    if ((i && (1 << x)) != 0)

or similar. Note that if i is something other than an integer you'll need a type suffix on the 1 in that expression, e.g. 1LL for long longs.

Hope that helps!
Rup.