1STRVERSCMP(3) Linux Programmer's Manual STRVERSCMP(3)
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6 strverscmp - compare two version strings
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9 #define _GNU_SOURCE
10 #include <string.h>
11 int strverscmp(const char *s1, const char *s2);
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15 Often one has files jan1, jan2, ..., jan9, jan10, ... and it feels
16 wrong when ls orders them jan1, jan10, ..., jan2, ..., jan9. In order
17 to rectify this, GNU introduced the -v option to ls(1), which is imple‐
18 mented using versionsort(3), which again uses strverscmp().
19 Thus, the task of strverscmp() is to compare two strings and find the
21 "right" order, while strcmp() only finds the lexicographic order. This
22 function does not use the locale category LC_COLLATE, so is meant
23 mostly for situations where the strings are expected to be in ASCII.
24 What this function does is the following. If both strings are equal,
26 return 0. Otherwise find the position between two bytes with the prop‐
27 erty that before it both strings are equal, while directly after it
28 there is a difference. Find the largest consecutive digit strings con‐
29 taining (or starting at, or ending at) this position. If one or both of
30 these is empty, then return what strcmp() would have returned (numeri‐
31 cal ordering of byte values). Otherwise, compare both digit strings
32 numerically, where digit strings with one or more leading zeroes are
33 interpreted as if they have a decimal point in front (so that in par‐
34 ticular digit strings with more leading zeroes come before digit
35 strings with fewer leading zeroes). Thus, the ordering is 000, 00, 01,
36 010, 09, 0, 1, 9, 10.
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39 The strverscmp() function returns an integer less than, equal to, or
40 greater than zero if s1 is found, respectively, to be earlier than,
41 equal to, or later than s2.
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44 This function is a GNU extension.
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47 rename(1), strcasecmp(3), strcmp(3), strcoll(3), feature_test_macros(7)
48GNU 2001-12-19 STRVERSCMP(3)