NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | SEE ALSO | COLOPHON
STRVERSCMP(3) Linux Programmer's Manual STRVERSCMP(3)
strverscmp - compare two version strings
#define _GNU_SOURCE
#include <string.h>
int strverscmp(const char *s1, const char *s2);
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.
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.
This function is a GNU extension.
rename(1), strcasecmp(3), strcmp(3), strcoll(3), feature_test_macros(7)
This page is part of release 3.23 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)