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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	imple-
       mented 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	 prop-
       erty  that  before  it  both strings are	equal, while directly after it
       there is	a difference.  Find the	largest	consecutive digit strings con-
       taining (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	numer-
       ically, where digit strings with	one or more leading zeroes are	inter-
       preted  as if they have a decimal point in front	(so that in particular
       digit strings with more leading zeroes come before digit	 strings  with
       fewer  leading 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)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | SEE ALSO

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