STRVERSCMP(3)		   Linux Programmers Manual		STRVERSCMP(3)



NAME
       strverscmp - compare two version strings

SYNOPSIS
       #define _GNU_SOURCE
       #include 

       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 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(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 3.05 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)