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anurag 07-20-2006 05:57 PM

print all permutations of string
 
hey can anyone help me in writing a code in c (function) that prints
all permutations of a string.please help


Victor Bazarov 07-20-2006 05:59 PM

Re: print all permutations of string
 
anurag wrote:
> hey can anyone help me in writing a code in c (function) that prints
> all permutations of a string.please help


Please, for C questions do not cross-post to comp.lang.c++. Thanks!

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask



Flash Gordon 07-20-2006 06:22 PM

Re: print all permutations of string
 
anurag wrote:
> hey can anyone help me in writing a code in c (function) that prints
> all permutations of a string.please help


Yes. First learn that C++ and C are different languages, so posting to
comp.lang.c++ is entirely inappropriate if you want a C solution.

Having excluded comp.lang.c++ you should first try to write your
algorithm. comp.lang.c does not generally help with algorithms,
comp.programming and alt.comp.lang.c-c++ might, check the groups out to
see. comp.lang.c discusses the C language and helps people with C problems.

Then, post specific questions rather than just asking someone to help
you writing it. A lot of us could write the function in less time that
it would take to explain it to you, but this would not help you to learn.

If you don't know where to start, then I suggest you start off by trying
to write all the permutations of a short string by hand rather than
trying to write a program to do it. Then you can analyse how you did it
and try to formalise that in to an algorithm.

I've excluded comp.lang.c++ from the follow-ups. When you have decided
whether you have a problem with the C language or with writing the
algorithm please cut the posting down to only the most appropriate group.
--
Flash Gordon, living in interesting times.
Web site - http://home.flash-gordon.me.uk/
comp.lang.c posting guidelines and intro:
http://clc-wiki.net/wiki/Intro_to_clc

Lew Pitcher 07-20-2006 06:41 PM

Re: print all permutations of string
 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


anurag wrote:
> hey can anyone help me in writing a code in c (function) that prints
> all permutations of a string.please help


IIRC, this favour has been requested a number of times in recent weeks.
I wonder why the sudden interest in permuting strings using C
functions.

In any case, to give a concrete example of what R.H. discusses
elsethread, here's an attempt I made a few weeks ago, when the question
first came up. Take it as you will.

For the regulars: yes I know that answering a homework question is
frowned apon, and even worse is answering an algorithm question, but
this one piqued my interest. So, for my one freebie a year, I post this
code ;-)

==snip==

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void rotate(unsigned length, char *string)
{
char save;

save = *string;
while(--length)
{
*string=*(string+1);
++string;
}
*string = save;
}

void permute(unsigned length, char *string, unsigned depth)
{

if (length == 0)
printf("%s\n",string-depth);
else
{
unsigned count;

for (count = length ; count > 0; --count)
{
permute(length-1,string+1,depth+1);
rotate(length,string);
}
}

}


int main(int argc, char **argv)
{
while (--argc)
{
char *source = malloc(strlen(*++argv)+1);

if (source)
{
strcpy(source,*argv);
printf("\nPermuting \"%s\"\n",source);

permute(strlen(source),source,0);

free(source);
}
}
return EXIT_SUCCESS;
}


==snip==

- --
Lew Pitcher


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Francis Glassborow 07-20-2006 08:52 PM

Re: print all permutations of string
 
In article <1153418276.122549.15570@m79g2000cwm.googlegroups. com>,
anurag <anurag1408@gmail.com> writes
>hey can anyone help me in writing a code in c (function) that prints
>all permutations of a string.please help
>


That looks like homework. In addition it is under specified. Are the
characters in the string all unique or are repeats allowed? If they are
all unique it is very easy :)

--
Francis Glassborow ACCU
Author of 'You Can Do It!' and "You Can Program in C++"
see http://www.spellen.org/youcandoit
For project ideas and contributions: http://www.spellen.org/youcandoit/projects

Keith Thompson 07-20-2006 09:46 PM

Re: print all permutations of string
 
Francis Glassborow <francis@robinton.demon.co.uk> writes:
> In article <1153418276.122549.15570@m79g2000cwm.googlegroups. com>,
> anurag <anurag1408@gmail.com> writes
>>hey can anyone help me in writing a code in c (function) that prints
>>all permutations of a string.please help
>>

>
> That looks like homework. In addition it is under specified. Are the
> characters in the string all unique or are repeats allowed? If they
> are all unique it is very easy :)


Not as easy as if they're all the same!

--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

Noah Roberts 07-20-2006 10:11 PM

Re: print all permutations of string
 

anurag wrote:
> hey can anyone help me in writing a code in c (function) that prints
> all permutations of a string.please help


Knuth, Volume 4 fascicle 2.


Alf P. Steinbach 07-20-2006 10:28 PM

Re: print all permutations of string
 
* Noah Roberts:
> anurag wrote:
>> hey can anyone help me in writing a code in c (function) that prints
>> all permutations of a string.please help

>
> Knuth, Volume 4 fascicle 2.


As I recall, Knuth does not discuss or mention arithmetic coding of
permutations (using the factorial number system), so is not a complete
reference.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

Ben Pfaff 07-20-2006 10:31 PM

Re: print all permutations of string
 
"Alf P. Steinbach" <alfps@start.no> writes:

> * Noah Roberts:
>> anurag wrote:
>>> hey can anyone help me in writing a code in c (function) that prints
>>> all permutations of a string.please help

>> Knuth, Volume 4 fascicle 2.

>
> As I recall, Knuth does not discuss or mention arithmetic coding of
> permutations (using the factorial number system), so is not a complete
> reference.


Is that necessary to answer the OP's question? I doubt it.
--
"doe not call up Any that you can not put downe."
--H. P. Lovecraft

Jon Clements 07-20-2006 10:36 PM

Re: print all permutations of string
 

Francis Glassborow wrote:
> In article <1153418276.122549.15570@m79g2000cwm.googlegroups. com>,
> anurag <anurag1408@gmail.com> writes
> >hey can anyone help me in writing a code in c (function) that prints
> >all permutations of a string.please help
> >

>
> That looks like homework. <snip>


(cross postings removed)

Strange, was a huge interest in this in comp.lang.python as well - just
the other week. Must be that bit of the course they've all gotten to!

Jon



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