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fea681da | 1 | .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl> |
1f73bfaf | 2 | .\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com> |
fea681da | 3 | .\" |
93015253 | 4 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
5 | .\" Permission is granted to make and distribute verbatim copies of this |
6 | .\" manual provided the copyright notice and this permission notice are | |
7 | .\" preserved on all copies. | |
8 | .\" | |
9 | .\" Permission is granted to copy and distribute modified versions of this | |
10 | .\" manual under the conditions for verbatim copying, provided that the | |
11 | .\" entire resulting derived work is distributed under the terms of a | |
12 | .\" permission notice identical to this one. | |
c13182ef | 13 | .\" |
fea681da MK |
14 | .\" Since the Linux kernel and libraries are constantly changing, this |
15 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
16 | .\" responsibility for errors or omissions, or for damages resulting from | |
17 | .\" the use of the information contained herein. The author(s) may not | |
18 | .\" have taken the same level of care in the production of this manual, | |
19 | .\" which is licensed free of charge, as they might when working | |
20 | .\" professionally. | |
c13182ef | 21 | .\" |
fea681da MK |
22 | .\" Formatted or processed versions of this manual, if unaccompanied by |
23 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 24 | .\" %%%LICENSE_END |
fea681da | 25 | .\" |
9ba01802 | 26 | .TH STRVERSCMP 3 2019-03-06 "GNU" "Linux Programmer's Manual" |
fea681da MK |
27 | .SH NAME |
28 | strverscmp \- compare two version strings | |
29 | .SH SYNOPSIS | |
30 | .nf | |
b80f966b | 31 | .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" |
fea681da | 32 | .B #include <string.h> |
68e4db0a | 33 | .PP |
fea681da MK |
34 | .BI "int strverscmp(const char *" s1 ", const char *" s2 ); |
35 | .fi | |
36 | .SH DESCRIPTION | |
37 | Often one has files | |
38 | .IR jan1 ", " jan2 ", ..., " jan9 ", " jan10 ", ..." | |
39 | and it feels wrong when | |
f19a0f03 | 40 | .BR ls (1) |
fea681da | 41 | orders them |
c10859eb | 42 | .IR jan1 ", " jan10 ", ..., " jan2 ", ..., " jan9 . |
fea681da MK |
43 | .\" classical solution: "rename jan jan0 jan?" |
44 | In order to rectify this, GNU introduced the | |
f19a0f03 | 45 | .I \-v |
fea681da MK |
46 | option to |
47 | .BR ls (1), | |
48 | which is implemented using | |
49 | .BR versionsort (3), | |
50 | which again uses | |
e511ffb6 | 51 | .BR strverscmp (). |
f47758ba | 52 | .PP |
fea681da | 53 | Thus, the task of |
e511ffb6 | 54 | .BR strverscmp () |
fea681da | 55 | is to compare two strings and find the "right" order, while |
fb186734 | 56 | .BR strcmp (3) |
33a0ccb2 | 57 | finds only the lexicographic order. |
c13182ef | 58 | This function does not use |
097585ed MK |
59 | the locale category |
60 | .BR LC_COLLATE , | |
61 | so is meant mostly for situations | |
fea681da | 62 | where the strings are expected to be in ASCII. |
f47758ba | 63 | .PP |
fea681da | 64 | What this function does is the following. |
c13182ef | 65 | If both strings are equal, return 0. |
2b9b829d | 66 | Otherwise, find the position |
fea681da MK |
67 | between two bytes with the property that before it both strings are equal, |
68 | while directly after it there is a difference. | |
69 | Find the largest consecutive digit strings containing (or starting at, | |
c13182ef MK |
70 | or ending at) this position. |
71 | If one or both of these is empty, | |
fea681da | 72 | then return what |
fb186734 | 73 | .BR strcmp (3) |
fea681da MK |
74 | would have returned (numerical ordering of byte values). |
75 | Otherwise, compare both digit strings numerically, where digit strings with | |
7b01461a MK |
76 | one or more leading zeros are interpreted as if they have a decimal point |
77 | in front (so that in particular digit strings with more leading zeros | |
78 | come before digit strings with fewer leading zeros). | |
fea681da MK |
79 | Thus, the ordering is |
80 | .IR 000 ", " 00 ", " 01 ", " 010 ", " 09 ", " 0 ", " 1 ", " 9 ", " 10 . | |
47297adb | 81 | .SH RETURN VALUE |
60a90ecd MK |
82 | The |
83 | .BR strverscmp () | |
84 | function returns an integer | |
c6fa0841 MK |
85 | less than, equal to, or greater than zero if |
86 | .I s1 | |
fea681da | 87 | is found, respectively, to be earlier than, equal to, |
c6fa0841 MK |
88 | or later than |
89 | .IR s2 . | |
9aa3ae0b PH |
90 | .SH ATTRIBUTES |
91 | For an explanation of the terms used in this section, see | |
92 | .BR attributes (7). | |
93 | .TS | |
94 | allbox; | |
95 | lb lb lb | |
96 | l l l. | |
97 | Interface Attribute Value | |
98 | T{ | |
99 | .BR strverscmp () | |
80189236 MK |
100 | T} Thread safety MT-Safe |
101 | .TE | |
102 | .\" FIXME: The marking is different from that in the glibc manual, | |
103 | .\" which has: | |
104 | .\" | |
105 | .\" strverscmp: MT-Safe locale | |
106 | .\" | |
72ab1faa MS |
107 | .\" glibc manual says strverscmp should have marking locale because it calls |
108 | .\" isdigit() multiple times and isdigit() uses locale variable. | |
109 | .\" But isdigit() has two implementations. With different compiling conditions, | |
110 | .\" we may call isdigit() in macro, then strverscmp() should not have locale | |
111 | .\" problem. | |
47297adb | 112 | .SH CONFORMING TO |
fea681da | 113 | This function is a GNU extension. |
1f73bfaf MK |
114 | .SH EXAMPLE |
115 | The program below can be used to demonstrate the behavior of | |
116 | .BR strverscmp (). | |
117 | It uses | |
118 | .BR strverscmp () | |
119 | to compare the two strings given as its command-line arguments. | |
120 | An example of its use is the following: | |
f47758ba | 121 | .PP |
1f73bfaf | 122 | .in +4n |
b8302363 | 123 | .EX |
0fd299bf | 124 | $ \fB./a.out jan1 jan10\fP |
1f73bfaf | 125 | jan1 < jan10 |
b8302363 | 126 | .EE |
1f73bfaf MK |
127 | .in |
128 | .SS Program source | |
129 | \& | |
e7d0bb47 | 130 | .EX |
1f73bfaf MK |
131 | #define _GNU_SOURCE |
132 | #include <string.h> | |
133 | #include <stdio.h> | |
134 | #include <stdlib.h> | |
135 | ||
136 | int | |
137 | main(int argc, char *argv[]) | |
138 | { | |
139 | int res; | |
140 | ||
141 | if (argc != 3) { | |
d1a71985 | 142 | fprintf(stderr, "Usage: %s <string1> <string2>\en", argv[0]); |
1f73bfaf MK |
143 | exit(EXIT_FAILURE); |
144 | } | |
145 | ||
146 | res = strverscmp(argv[1], argv[2]); | |
147 | ||
d1a71985 | 148 | printf("%s %s %s\en", argv[1], |
729b84f4 | 149 | (res < 0) ? "<" : (res == 0) ? "==" : ">", argv[2]); |
1f73bfaf MK |
150 | |
151 | exit(EXIT_SUCCESS); | |
152 | } | |
e7d0bb47 | 153 | .EE |
47297adb | 154 | .SH SEE ALSO |
fea681da MK |
155 | .BR rename (1), |
156 | .BR strcasecmp (3), | |
157 | .BR strcmp (3), | |
0a4f8b7b | 158 | .BR strcoll (3) |