strverscmp(3) — Linux manual page


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

       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

       │Interface    Attribute     Value   │
       │strverscmp() │ Thread safety │ MT-Safe │

CONFORMING TO         top

       This function is a GNU extension.

EXAMPLES         top

       The program below can be used to demonstrate the behavior of
       strverscmp().  It uses strverscmp() to compare the two strings given
       as its command-line arguments.  An example of its use is the

           $ ./a.out jan1 jan10
           jan1 < jan10

   Program source

       #define _GNU_SOURCE
       #include <string.h>
       #include <stdio.h>
       #include <stdlib.h>

       main(int argc, char *argv[])
           int res;

           if (argc != 3) {
               fprintf(stderr, "Usage: %s <string1> <string2>\n", argv[0]);

           res = strverscmp(argv[1], argv[2]);

           printf("%s %s %s\n", argv[1],
                   (res < 0) ? "<" : (res == 0) ? "==" : ">", argv[2]);


SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.08 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

GNU                              2020-06-09                    STRVERSCMP(3)

Pages that refer to this page: alphasort(3)scandir(3)scandirat(3)strcmp(3)strncmp(3)versionsort(3)mount(8)