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1 | .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl> |
2 | .\" | |
4b72fb64 | 3 | .\" %%%LICENSE_START(verbatim) |
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4 | .\" Permission is granted to make and distribute verbatim copies of this |
5 | .\" manual provided the copyright notice and this permission notice are | |
6 | .\" preserved on all copies. | |
7 | .\" | |
8 | .\" Permission is granted to copy and distribute modified versions of this | |
9 | .\" manual under the conditions for verbatim copying, provided that the | |
10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
c13182ef | 12 | .\" |
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13 | .\" Since the Linux kernel and libraries are constantly changing, this |
14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
15 | .\" responsibility for errors or omissions, or for damages resulting from | |
16 | .\" the use of the information contained herein. The author(s) may not | |
17 | .\" have taken the same level of care in the production of this manual, | |
18 | .\" which is licensed free of charge, as they might when working | |
19 | .\" professionally. | |
c13182ef | 20 | .\" |
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21 | .\" Formatted or processed versions of this manual, if unaccompanied by |
22 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 23 | .\" %%%LICENSE_END |
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24 | .\" |
25 | .TH STRVERSCMP 3 2001-12-19 "GNU" "Linux Programmer's Manual" | |
26 | .SH NAME | |
27 | strverscmp \- compare two version strings | |
28 | .SH SYNOPSIS | |
29 | .nf | |
b80f966b | 30 | .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" |
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31 | .br |
32 | .B #include <string.h> | |
33 | .sp | |
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 . |
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43 | .\" classical solution: "rename jan jan0 jan?" |
44 | In order to rectify this, GNU introduced the | |
f19a0f03 | 45 | .I \-v |
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46 | option to |
47 | .BR ls (1), | |
48 | which is implemented using | |
49 | .BR versionsort (3), | |
50 | which again uses | |
e511ffb6 | 51 | .BR strverscmp (). |
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52 | |
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) |
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57 | only finds the lexicographic order. |
58 | This function does not use | |
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59 | the locale category |
60 | .BR LC_COLLATE , | |
61 | so is meant mostly for situations | |
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62 | where the strings are expected to be in ASCII. |
63 | ||
64 | What this function does is the following. | |
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65 | If both strings are equal, return 0. |
66 | Otherwise find the position | |
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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, | |
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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) |
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74 | would have returned (numerical ordering of byte values). |
75 | Otherwise, compare both digit strings numerically, where digit strings with | |
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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). | |
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79 | Thus, the ordering is |
80 | .IR 000 ", " 00 ", " 01 ", " 010 ", " 09 ", " 0 ", " 1 ", " 9 ", " 10 . | |
47297adb | 81 | .SH RETURN VALUE |
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82 | The |
83 | .BR strverscmp () | |
84 | function returns an integer | |
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85 | less than, equal to, or greater than zero if \fIs1\fP |
86 | is found, respectively, to be earlier than, equal to, | |
87 | or later than \fIs2\fP. | |
47297adb | 88 | .SH CONFORMING TO |
fea681da | 89 | This function is a GNU extension. |
47297adb | 90 | .SH SEE ALSO |
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91 | .BR rename (1), |
92 | .BR strcasecmp (3), | |
93 | .BR strcmp (3), | |
0a4f8b7b | 94 | .BR strcoll (3) |