linux man page for strverscmp

STRVERSCMP(3)						     Linux Programmer's Manual						     STRVERSCMP(3)

NAME
       strverscmp - compare two version strings

SYNOPSIS
       #define _GNU_SOURCE
       #include <string.h>

       int strverscmp(const char *s1, const char *s2);

DESCRIPTION
       Often  one  has	files  jan1, jan2, ..., jan9, jan10, ...  and it feels wrong when ls(1) orders them jan1, jan10, ..., jan2, ..., jan9.	In
       order to rectify this, GNU introduced the -v option to ls(1), which is implemented using versionsort(3), which again uses strverscmp().

       Thus, the task of strverscmp() is to compare two strings and find the "right" order, while strcmp(3) only finds	the  lexicographic  order.
       This function does not use the locale category LC_COLLATE, so is meant mostly for situations where the strings are expected to be in ASCII.

       What  this  function  does  is the following.  If both strings are equal, return 0.  Otherwise find the position between two bytes with the
       property that before it both strings are equal, while directly after it there is a difference.  Find the largest consecutive digit  strings
       containing  (or starting at, or ending at) this position.  If one or both of these is empty, then return what strcmp(3) would have returned
       (numerical ordering of byte values).  Otherwise, compare both digit strings numerically, where digit strings with one or more leading zeros
       are  interpreted  as  if  they have a decimal point in front (so that in particular digit strings with more leading zeros come before digit
       strings with fewer leading zeros).  Thus, the ordering is 000, 00, 01, 010, 09, 0, 1, 9, 10.

RETURN VALUE
       The strverscmp() function returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to	be  earlier  than,
       equal to, or later than s2.

CONFORMING TO
       This function is a GNU extension.

SEE ALSO
       rename(1), strcasecmp(3), strcmp(3), strcoll(3), feature_test_macros(7)

COLOPHON
       This  page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2001-12-19							     STRVERSCMP(3)