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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(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 numeri-
       cally,  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 3.22 of the Linux man-pages project.  A description of
       the  project, and information about reporting bugs, can be found at http://www.ker-
       nel.org/doc/man-pages/.



GNU                               2001-12-19                     STRVERSCMP(3)

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