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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | EXAMPLES | SEE ALSO | COLOPHON |
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strverscmp(3) Library Functions Manual strverscmp(3)
strverscmp - compare two version strings
Standard C library (libc, -lc)
#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 │
└─────────────────────────────────────┴───────────────┴─────────┘
GNU.
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:
$ ./a.out jan1 jan10
jan1 < jan10
Program source
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.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 the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-06-15 strverscmp(3)
Pages that refer to this page: scandir(3), strcmp(3), mount(8), swapon(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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