Sunday, November 29, 2015

Digest for comp.lang.c++@googlegroups.com - 9 updates in 2 topics

MikeCopeland <mrc2323@cox.net>: Nov 29 01:27PM -0700

Is there a way to initialize a non-contiguous number of bits in a
std::bitset (other than with a string of 0 or 1 bits with those desired
bits as 1)? That is, I have a declration of:
std::bitset<100> myBits;
and I want to set the following bits:
7, 9, 43, 47, 51-59, 66, 67
I can, of course, construct a string constant of these bits, but it's
tedious to code and completely lacking in good documentation...
Is there an easy way to do so in source code? TIA
 
 
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BartC <bc@freeuk.com>: Nov 29 09:19PM

On 29/11/2015 20:27, MikeCopeland wrote:
> I can, of course, construct a string constant of these bits, but it's
> tedious to code and completely lacking in good documentation...
> Is there an easy way to do so in source code? TIA
 
I just saw this post by chance and know nothing of the capabilities of C++.
 
But your requirement reminds me of the Pascal way to do the same:
 
var myBits: set of 1..100;
 
myBits := [7, 9, 43, 47, 51..59, 66, 67];
 
So exactly as you've denoted except for using .. for the range (I assume
you don't mean -8).
 
This can serve as a target anyway.
 
--
Bartc
Paavo Helde <myfirstname@osa.pri.ee>: Nov 29 04:07PM -0600

MikeCopeland <mrc2323@cox.net> wrote in news:MPG.30c50d893dd76c039896b7
> and I want to set the following bits:
> 7, 9, 43, 47, 51-59, 66, 67
> I can, of course, construct a string constant of these bits, but
it's
> tedious to code and completely lacking in good documentation...
> Is there an easy way to do so in source code? TIA
 
Not quite one line, but close (C++11):
 
#include <iostream>
#include <bitset>
 
int main() {
std::bitset<100> mybitset;
for (auto bit:
{7, 9, 43, 47, 51, 52, 53, 54, 55, 56, 57, 58, 59, 66, 67})
{
mybitset.set(bit);
}

std::cout << mybitset.to_string() << "\n";
}
 
or more fancy & verbose:
 
#include <iostream>
#include <numeric>
#include <bitset>
#include <iterator>
 
int main() {
using b100 = std::bitset<100>;
 
const int bits[] =
{7, 9, 43, 47, 51, 52, 53, 54, 55, 56, 57, 58, 59, 66, 67};
 
b100 mybitset =
std::accumulate(std::begin(bits), std::end(bits), b100(),
[](b100 bset, int bit) {bset.set(bit); return bset; });
 
std::cout << mybitset.to_string() << "\n";
}
Geoff <geoff@invalid.invalid>: Nov 29 03:31PM -0800

On Sun, 29 Nov 2015 13:27:11 -0700, MikeCopeland <mrc2323@cox.net>
wrote:
 
> I can, of course, construct a string constant of these bits, but it's
>tedious to code and completely lacking in good documentation...
> Is there an easy way to do so in source code? TIA
 
I don't see a way to express the range 51-59 but here's my solution:
 
#include <iostream>
#include <bitset>
 
int main (void)
{
std::bitset<100> myBits;
const int mySets[] =
{7, 9, 43, 47, 51, 52, 53, 54, 55, 56, 57, 58, 59, 66, 67};
 
for (int i = 0; i < sizeof(mySets)/sizeof(int); i++)
myBits.set(mySets[i]);
 
std::cout << "Bits ";
for (size_t i = 0; i < myBits.size(); i++) {
if (myBits.test(i)) {
std::cout << i << " ";
}
}
std::cout << "are set." << std::endl;
}
Lynn McGuire <lmc@winsim.com>: Nov 29 01:42PM -0600

On 8/19/2015 3:46 AM, Juha Nieminen wrote:
> moderately successful, the vast majority of them have been forgotten.
> But they are still better than C++, dammit!
 
> --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
C was the first computer language to successfully change from line
oriented (Fortran, Cobol, etc) to byte oriented. And, then C++ jumped
from pure procedural to object oriented. All in all, good enough. And
the high speed of the resultant programs is a big plus.
 
Lynn
Bo Persson <bop@gmb.dk>: Nov 29 11:14PM +0100

On 2015-11-29 20:42, Lynn McGuire wrote:
> oriented (Fortran, Cobol, etc) to byte oriented. And, then C++ jumped
> from pure procedural to object oriented. All in all, good enough. And
> the high speed of the resultant programs is a big plus.
 
No, it wasn't.
 
C++ is inspired by the classes of Simula 67, which is an extension of
Algol 60.
 
 
Bo Persson
Lynn McGuire <lmc@winsim.com>: Nov 29 04:22PM -0600

On 11/29/2015 4:14 PM, Bo Persson wrote:
 
> C++ is inspired by the classes of Simula 67, which is an extension of
> Algol 60.
 
> Bo Persson
 
Sorry, Algol was not a successful computer language.
 
Lynn
Robert Wessel <robertwessel2@yahoo.com>: Nov 29 04:32PM -0600

On Sun, 29 Nov 2015 16:22:39 -0600, Lynn McGuire <lmc@winsim.com>
wrote:
 
>> Algol 60.
 
>> Bo Persson
 
>Sorry, Algol was not a successful computer language.
 
 
Sure it was. Just not in the US.
Lynn McGuire <lmc@winsim.com>: Nov 29 05:00PM -0600

On 11/29/2015 4:32 PM, Robert Wessel wrote:
 
>>> Bo Persson
 
>> Sorry, Algol was not a successful computer language.
 
> Sure it was. Just not in the US.
 
I don't even regard Pascal as a successful language and I wrote software
in Turbo Pascal for half a decade.
 
Lynn
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