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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 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 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 would have returned (numerical ordering of byte values).
       Otherwise,  compare  both  digit strings numerically, where digit strings with one or more
       leading zeroes are interpreted as if they have a decimal point in front (so that  in  par-
       ticular	digit strings with more leading zeroes come before digit strings with fewer lead-
       ing zeroes).  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)

GNU					    2001-12-19				    STRVERSCMP(3)
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