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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | EXAMPLE | SEE ALSO | COLOPHON |
STRVERSCMP(3) Linux Programmer's Manual STRVERSCMP(3)
strverscmp - compare two version strings
#define _GNU_SOURCE /* See feature_test_macros(7) */
#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) 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.
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.
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├─────────────┼───────────────┼─────────┤
│strverscmp() │ Thread safety │ MT-Safe │
└─────────────┴───────────────┴─────────┘
This function is a GNU extension.
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
following:
$ i./a.out jan1 jan10
jan1 < jan10
Program source
#define _GNU_SOURCE
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
int res;
if (argc != 3) {
fprintf(stderr, "Usage: %s <string1> <string2>\n", argv[0]);
exit(EXIT_FAILURE);
}
res = strverscmp(argv[1], argv[2]);
printf("%s %s %s\n", argv[1],
(res < 0) ? "<" : (res == 0) ? "==" : ">", argv[2]);
exit(EXIT_SUCCESS);
}
rename(1), strcasecmp(3), strcmp(3), strcoll(3)
This page is part of release 4.12 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 2017-03-13 STRVERSCMP(3)
Pages that refer to this page: scandir(3), strcmp(3)