STRVERSCMP(3) Linux Programmer's Manual STRVERSCMP(3)NAMEstrverscmp - compare two version strings
SYNOPSIS
#define _GNU_SOURCE
#include <string.h>
int strverscmp(const char *s1, const char *s2);
DESCRIPTION
Often one has files jan1, jan2, ..., jan9, jan10, ... and it feels
wrong when ls orders them jan1, jan10, ..., jan2, ..., jan9. In order
to rectify this, GNU introduced the -v option to ls(1), which is imple‐
mented using versionsort(3), which again uses strverscmp().
Thus, the task of strverscmp() is to compare two strings and find the
"right" order, while strcmp() 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 prop‐
erty that before it both strings are equal, while directly after it
there is a difference. Find the largest consecutive digit strings con‐
taining (or starting at, or ending at) this position. If one or both of
these is empty, then return what strcmp() would have returned (numeri‐
cal ordering of byte values). Otherwise, compare both digit strings
numerically, where digit strings with one or more leading zeroes are
interpreted as if they have a decimal point in front (so that in par‐
ticular digit strings with more leading zeroes come before digit
strings with fewer leading zeroes). Thus, the ordering is 000, 00, 01,
010, 09, 0, 1, 9, 10.
RETURN VALUE
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.
CONFORMING TO
This function is a GNU extension.
SEE ALSOrename(1), strcasecmp(3), strcmp(3), strcoll(3)GNU 2001-12-19 STRVERSCMP(3)
