Determine if a character string is palindromic

[lovecreatesbeauty]

Hello experts,

I write a function named palindrome to determine if a character string
is palindromic, and test it with some example strings. Is it suitable
to add it to a company/project library as a small tool function
according to its quality? I will be very happy to get your suggestion
from every aspect on it: interface design, C language knowledge or
algorithm efficient.

Sincerely,

lovecreatesbeau ty
/* Filename : palindrome.c
* Function : bool palindrome(char *s);
* Description: to determine if a character string is palindromic
* Date : 8 May 2006
*/

#include <stdbool.h>
#include <stddef.h>
#include <string.h>

bool palindrome(char *s)
{
bool palindromic = true;
size_t len = strlen(s);

if (len > 1)
{
for (unsigned i = 0; i < len / 2; ++i)
{
if (s[i] != s[len - 1 - i])
{
palindromic = false;
break;
}
}
}

return palindromic;
}
/* test */
#include <stdio.h>

int main()
{
printf("%i\n", palindrome("dee d"));
printf("%i\n", palindrome("dee ds"));
}

/*
$ gcc -W -Wall -std=c99 -pedantic palindrome.c
$ ./a.out
1
0
$
*/

[Simon Biber]

Richard Heathfield wrote:

Simon Biber said:

Richard Heathfield wrote:

You might want to test it with these well-known palindromes:

"Madam, I'm Adam!"
"Able was I, ere I saw Elba."
"A man, a plan, a canal - Panama!"

They are palindromic sentences, not palindromic strings.

They are palindromes.

Sure, but the original program did not claim to detect palindromes. It
claimed to detect palindromic strings. :-)

void convert_sentenc e_to_string(cha r *destination, const char *source)
{
for(; *source; source++)
{
if(isalpha((uns igned char) *source))
*destination++ = toupper((unsign ed char) *source);
}
}

And when were you planning on fixing the bug? :-)

Apart from the failure to include <ctype.h>, was there a bug in my code?

Simon.

[Richard Heathfield]

Simon Biber said:

Richard Heathfield wrote:

Simon Biber said:

void convert_sentenc e_to_string(cha r *destination, const char *source)
{
for(; *source; source++)
{
if(isalpha((uns igned char) *source))
*destination++ = toupper((unsign ed char) *source);
}
}

And when were you planning on fixing the bug? :-)

Apart from the failure to include <ctype.h>, was there a bug in my code?

Yep. Here's a hint. The name of the function gives the intent, but the code
does not meet that intent. You have forgotten something rather important,
as a result of which disaster could well strike. In fact, it's a terminal
error!

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

[Simon Biber]

Richard Heathfield wrote:

Simon Biber said:

Richard Heathfield wrote:

Simon Biber said:

void convert_sentenc e_to_string(cha r *destination, const char *source)
{
for(; *source; source++)
{
if(isalpha((uns igned char) *source))
*destination++ = toupper((unsign ed char) *source);
}
}

And when were you planning on fixing the bug? :-)

Apart from the failure to include <ctype.h>, was there a bug in my code?

Yep. Here's a hint. The name of the function gives the intent, but the code
does not meet that intent. You have forgotten something rather important,
as a result of which disaster could well strike. In fact, it's a terminal
error!

Ah, yes. I am getting sloppy!

Insert a line
*destination = 0;
as the last line of the function.

I will admit that I had not tested the function the first time I posted
it. I did test it after your comment about a bug, but unfortunately it
worked fine. There must have been a serendipitous null byte in my array.

--
Simon.

[Chris F.A. Johnson]

On 2006-05-09, Flash Gordon wrote:

Chris F.A. Johnson wrote:

On 2006-05-08, Keith Thompson wrote:

(Chris, just out of curiosity, why do you always indent everything you
write?

For the same reason that books have margins, and better books wider
margins.

My news reader provides such indentation sufficient unto my needs. I
could probably configure it to provide more if I so desired. This does
not require that you indent your text.

Actaully, I started doing it in order to distinguish between my
text and (shell) code. I like code set flush left so that no
fiddling is necessary when cutting and pasting it.

Personally I find shells don't have a problem with white space before
the commands.

It would if the command, intending IFS to contain a single newline,
is:

IFS='
'

I have the same problem if I have my newsreader do the indentation.

--
Chris F.A. Johnson, author <http://cfaj.freeshell. org>
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence

[Keith Thompson]

"Chris F.A. Johnson" <cf********@gma il.com> writes:

On 2006-05-09, Flash Gordon wrote:

Chris F.A. Johnson wrote:

On 2006-05-08, Keith Thompson wrote:

(Chris, just out of curiosity, why do you always indent everything you
write?

For the same reason that books have margins, and better books wider
margins.

My news reader provides such indentation sufficient unto my needs. I
could probably configure it to provide more if I so desired. This does
not require that you indent your text.

Actaully, I started doing it in order to distinguish between my
text and (shell) code. I like code set flush left so that no
fiddling is necessary when cutting and pasting it.

Personally I find shells don't have a problem with white space before
the commands.

It would if the command, intending IFS to contain a single newline,
is:

IFS='
'

I have the same problem if I have my newsreader do the indentation.

Since you're the only person I know of who does this, it makes your
posts, and posts that quote them, slightly more difficult to read.
I suggest not indenting your text and finding some other way to mark
code.

It's not a huge deal, and I don't plan to bring it up again. Sorry
for the digression.

--
Keith Thompson (The_Other_Keit h) ks***@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.

[Denis Kasak]

Vladimir Oka wrote:

Apart from the fact that it doesn't work, it looks fairly good.
Did you consider upper/lower case? Try: "Ana voli Milovana".
Or, alternatively, you need to define "palindrome " more precisely.

After seeing this example, I'm curious; where are you from?