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

STRVERSCMP(3)             Linux Programmer's Manual            STRVERSCMP(3)

NAME         top

       strverscmp - compare two version strings

SYNOPSIS         top

       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <string.h>

       int strverscmp(const char *s1, const char *s2);

DESCRIPTION         top

       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) finds only 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.

RETURN VALUE         top

       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.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌─────────────┬───────────────┬─────────┐
       │Interface    Attribute     Value   │
       ├─────────────┼───────────────┼─────────┤
       │strverscmp() │ Thread safety │ MT-Safe │
       └─────────────┴───────────────┴─────────┘

CONFORMING TO         top

       This function is a GNU extension.

SEE ALSO         top

       rename(1), strcasecmp(3), strcmp(3), strcoll(3)

COLOPHON         top

       This page is part of release 4.07 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                              2015-03-02                    STRVERSCMP(3)