Fw: Suggestion for edit

Fw: Suggestion for edit

[Andrew Micallef]

Hi,


I'd like to suggest an edit to the description of `strcmp` in the standard C library man page.
I found this description to be kind of confusing, and think the language could be a bit more
straight forward. 



 At present the description reads as follows:

The strcmp() function compares the two strings s1 and s2.  The locale
       is not taken into account (for a locale-aware comparison, see
       strcoll(3)).  It returns an integer less than, equal to, or greater
       than zero if s1 is found, respectively, to be less than, to match, or
       be greater than s2.

I am suggesting the following edits:

The strcmp() function compares the two strings s1 and s2.  The locale
       is not taken into account (for a locale-aware comparison, see
       strcoll(3)).  It returns an integer, which is 0 if the strings 
       match. Otherwise, a negative integer indicates s1 is less than s2,
       while a positive integer indicates s1 is greater than s2.


Regards
Andrew

Re: Fw: Suggestion for edit

[Ponnuvel Palaniyappan]

Hi,

That part of the description is directly taken from the C standard
(nearly verbatim). It's terse but quite clear though.

Thanks,
Ponnuvel


On Tue, Apr 7, 2020 at 8:08 AM Andrew Micallef
<andrew.micallef@live.com.au> wrote:
>
> Hi,
>
>
> I'd like to suggest an edit to the description of `strcmp` in the standard C library man page.
> I found this description to be kind of confusing, and think the language could be a bit more
> straight forward.
>
>
>
>  At present the description reads as follows:
>
> The strcmp() function compares the two strings s1 and s2.  The locale
>        is not taken into account (for a locale-aware comparison, see
>        strcoll(3)).  It returns an integer less than, equal to, or greater
>        than zero if s1 is found, respectively, to be less than, to match, or
>        be greater than s2.
>
> I am suggesting the following edits:
>
> The strcmp() function compares the two strings s1 and s2.  The locale
>        is not taken into account (for a locale-aware comparison, see
>        strcoll(3)).  It returns an integer, which is 0 if the strings
>        match. Otherwise, a negative integer indicates s1 is less than s2,
>        while a positive integer indicates s1 is greater than s2.
>
>
> Regards
> Andrew
>


-- 
Regards,
Ponnuvel P

AW: Suggestion for edit

[Walter Harms]

hi Andrew, i have to admit that i dropped over the last sentence. And it should be *very* clear what the return means,
ehre my idea:

If both strings are equal the function returns 0.
Otherwises it returns the differences between the last compared characters.

The last feature is important for sorting. I never found a good wording for that.

re,
 wh



________________________________________
Von: linux-man-owner@vger.kernel.org <linux-man-owner@vger.kernel.org> im Auftrag von Andrew Micallef <andrew.micallef@live.com.au>
Gesendet: Dienstag, 7. April 2020 09:07:50
An: linux-man@vger.kernel.org
Betreff: Fw: Suggestion for edit

Hi,


I'd like to suggest an edit to the description of `strcmp` in the standard C library man page.
I found this description to be kind of confusing, and think the language could be a bit more
straight forward.



 At present the description reads as follows:

The strcmp() function compares the two strings s1 and s2.  The locale
       is not taken into account (for a locale-aware comparison, see
       strcoll(3)).  It returns an integer less than, equal to, or greater
       than zero if s1 is found, respectively, to be less than, to match, or
       be greater than s2.

I am suggesting the following edits:

The strcmp() function compares the two strings s1 and s2.  The locale
       is not taken into account (for a locale-aware comparison, see
       strcoll(3)).  It returns an integer, which is 0 if the strings
       match. Otherwise, a negative integer indicates s1 is less than s2,
       while a positive integer indicates s1 is greater than s2.


Regards
Andrew

Re: Suggestion for edit

[Andrew Micallef]

Hi Walter


Actually that new phrasing on the last sentence is much clearer. I was scratching my head over what it meant for a string to be less than (or greater than) another string. 

Cheers
Andrew




From: Walter Harms <wharms@bfs.de>

Sent: Tuesday, 7 April 2020 7:17 PM

To: Andrew Micallef <andrew.micallef@live.com.au>; linux-man@vger.kernel.org <linux-man@vger.kernel.org>

Subject: AW: Suggestion for edit

 


hi Andrew, i have to admit that i dropped over the last sentence. And it should be *very* clear what the return means,

ehre my idea:



If both strings are equal the function returns 0.

Otherwises it returns the differences between the last compared characters.



The last feature is important for sorting. I never found a good wording for that.



re,

 wh







________________________________________

Von: linux-man-owner@vger.kernel.org <linux-man-owner@vger.kernel.org> im Auftrag von Andrew Micallef <andrew.micallef@live.com.au>

Gesendet: Dienstag, 7. April 2020 09:07:50

An: linux-man@vger.kernel.org

Betreff: Fw: Suggestion for edit



Hi,





I'd like to suggest an edit to the description of `strcmp` in the standard C library man page.

I found this description to be kind of confusing, and think the language could be a bit more

straight forward.







 At present the description reads as follows:



The strcmp() function compares the two strings s1 and s2.  The locale

       is not taken into account (for a locale-aware comparison, see

       strcoll(3)).  It returns an integer less than, equal to, or greater

       than zero if s1 is found, respectively, to be less than, to match, or

       be greater than s2.



I am suggesting the following edits:



The strcmp() function compares the two strings s1 and s2.  The locale

       is not taken into account (for a locale-aware comparison, see

       strcoll(3)).  It returns an integer, which is 0 if the strings

       match. Otherwise, a negative integer indicates s1 is less than s2,

       while a positive integer indicates s1 is greater than s2.





Regards

Andrew

AW: Suggestion for edit

[Walter Harms]

the posix page is more direct about that.

"The sign of a non-zero return value shall be determined by the sign of the difference between the values of the first  pair  of     bytes (both interpreted as type unsigned char) that differ in the strings being compared."

re,
 wh
________________________________________
Von: Andrew Micallef <andrew.micallef@live.com.au>
Gesendet: Dienstag, 7. April 2020 11:45:03
An: Walter Harms; linux-man@vger.kernel.org
Betreff: Re: Suggestion for edit

Hi Walter


Actually that new phrasing on the last sentence is much clearer. I was scratching my head over what it meant for a string to be less than (or greater than) another string.

Cheers
Andrew




From: Walter Harms <wharms@bfs.de>

Sent: Tuesday, 7 April 2020 7:17 PM

To: Andrew Micallef <andrew.micallef@live.com.au>; linux-man@vger.kernel.org <linux-man@vger.kernel.org>

Subject: AW: Suggestion for edit




hi Andrew, i have to admit that i dropped over the last sentence. And it should be *very* clear what the return means,

ehre my idea:



If both strings are equal the function returns 0.

Otherwises it returns the differences between the last compared characters.



The last feature is important for sorting. I never found a good wording for that.



re,

 wh







________________________________________

Von: linux-man-owner@vger.kernel.org <linux-man-owner@vger.kernel.org> im Auftrag von Andrew Micallef <andrew.micallef@live.com.au>

Gesendet: Dienstag, 7. April 2020 09:07:50

An: linux-man@vger.kernel.org

Betreff: Fw: Suggestion for edit



Hi,





I'd like to suggest an edit to the description of `strcmp` in the standard C library man page.

I found this description to be kind of confusing, and think the language could be a bit more

straight forward.







 At present the description reads as follows:



The strcmp() function compares the two strings s1 and s2.  The locale

       is not taken into account (for a locale-aware comparison, see

       strcoll(3)).  It returns an integer less than, equal to, or greater

       than zero if s1 is found, respectively, to be less than, to match, or

       be greater than s2.



I am suggesting the following edits:



The strcmp() function compares the two strings s1 and s2.  The locale

       is not taken into account (for a locale-aware comparison, see

       strcoll(3)).  It returns an integer, which is 0 if the strings

       match. Otherwise, a negative integer indicates s1 is less than s2,

       while a positive integer indicates s1 is greater than s2.





Regards

Andrew

Re: Suggestion for edit

[Michael Kerrisk (man-pages)]

Hello Andrew,

On 4/7/20 6:06 AM, Andrew Micallef wrote:
> Hi Michael,
> 
> I'd like to suggest an edit to the description of `strcmp` in the standard C library man page.
> I found this description to be kind of confusing, and think the language could be a bit more
> straight forward.
>  At present the description reads as follows:
> 
> The strcmp() function compares the two strings s1 and s2.  The locale
>        is not taken into account (for a locale-aware comparison, see
>        strcoll(3)<http://man7.org/linux/man-pages/man3/strcoll.3.html>).
>        It returns an integer less than, equal to, or greater
>        than zero if s1 is found, respectively, to be less than, to match, or
>        be greater than s2.
> 
> I am suggesting the following edits:
> 
> The strcmp() function compares the two strings s1 and s2.  The locale
>        is not taken into account (for a locale-aware comparison, see
>        strcoll(3)<http://man7.org/linux/man-pages/man3/strcoll.3.html>).
>        It returns an integer, which is 0 if the strings
>        match. Otherwise, a negative integer indicates s1 is less than s2,
>        while a positive integer indicates s1 is greater than s2.

As Ponnuvel points out, the text pretty much matches POSIX. It is terse,
and clear. But also not so easy to parse, at least for some of us.

Furthermore, the text is essentially repeated twice in the page,
once in DESCRIPTION and then again in RETURN VALUE. Let's fix one of
those in the direction you suggest.

Also, I like Walter's suggestion of mentioning the arithmetic
difference.

How about this:

DESCRIPTION
       The  strcmp()  function  compares  the two strings s1 and s2.  The
       locale is not taken into account (for a  locale-aware  comparison,
       see  strcoll(3)).   The  comparison is done using unsigned charac‐
       ters.

*      strcmp() returns an integer indicating the result of the  compari‐
*       son, as follows:
*
*      · 0, if the s1 and s2 are equal;
*
*      · a negative value if s1 is less than s2;
*
*      · a positive value if s1 is greater than s2;

       The  strncmp()  function  is  similar, except it compares only the
       first (at most) n bytes of s1 and s2.

RETURN VALUE
       The strcmp() and strncmp() functions return an integer less  than,
       equal  to,  or  greater  than  zero  if  s1  (or the first n bytes
       thereof) is found, respectively, to be less than, to match, or  be
       greater than s2.

...

NOTES
*      POSIX.1 specifies only that:
*            The sign of a non-zero return value shall be determined  by
*             the  sign of the difference between the values of the first
*             pair of bytes (both interpreted as type unsigned char) that
*             differ in the strings being compared.
*
*      In  glibc,  as  in most other implementations, the return value is
*      the arithmetic result of subtracting the last  compared  character
*      in s2 from the last compared character in s1.  (If the two charac‐
*      ters are equal, this difference is 0.)

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/