1STRLEN(3P)                 POSIX Programmer's Manual                STRLEN(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       strlen, strnlen — get length of fixed size string
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SYNOPSIS

15       #include <string.h>
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17       size_t strlen(const char *s);
18       size_t strnlen(const char *s, size_t maxlen);
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DESCRIPTION

21       For strlen(): The functionality described on  this  reference  page  is
22       aligned  with the ISO C standard. Any conflict between the requirements
23       described here and the ISO C standard is unintentional. This volume  of
24       POSIX.1‐2017 defers to the ISO C standard.
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26       The  strlen()  function shall compute the number of bytes in the string
27       to which s points, not including the terminating NUL character.
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29       The strnlen() function shall compute the smaller of the number of bytes
30       in the array to which s points, not including any terminating NUL char‐
31       acter, or the value of the  maxlen  argument.  The  strnlen()  function
32       shall  never  examine more than maxlen bytes of the array pointed to by
33       s.
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RETURN VALUE

36       The strlen() function shall return the length of  s;  no  return  value
37       shall be reserved to indicate an error.
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39       The  strnlen()  function shall return the number of bytes preceding the
40       first null byte in the array to which s points, if s  contains  a  null
41       byte within the first maxlen bytes; otherwise, it shall return maxlen.
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ERRORS

44       No errors are defined.
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46       The following sections are informative.
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EXAMPLES

49   Getting String Lengths
50       The  following example sets the maximum length of key and data by using
51       strlen() to get the lengths of those strings.
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54           #include <string.h>
55           ...
56           struct element {
57               char *key;
58               char *data;
59           };
60           ...
61           char *key, *data;
62           int len;
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64           *keylength = *datalength = 0;
65           ...
66           if ((len = strlen(key)) > *keylength)
67               *keylength = len;
68           if ((len = strlen(data)) > *datalength)
69               *datalength = len;
70           ...
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APPLICATION USAGE

73       None.
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RATIONALE

76       None.
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FUTURE DIRECTIONS

79       None.
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SEE ALSO

82       wcslen()
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84       The Base Definitions volume of POSIX.1‐2017, <string.h>
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87       Portions of this text are reprinted and reproduced in  electronic  form
88       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
89       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
90       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
91       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
92       event of any discrepancy between this version and the original IEEE and
93       The Open Group Standard, the original IEEE and The Open Group  Standard
94       is  the  referee document. The original Standard can be obtained online
95       at http://www.opengroup.org/unix/online.html .
96
97       Any typographical or formatting errors that appear  in  this  page  are
98       most likely to have been introduced during the conversion of the source
99       files to man page format. To report such errors,  see  https://www.ker‐
100       nel.org/doc/man-pages/reporting_bugs.html .
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104IEEE/The Open Group                  2017                           STRLEN(3P)
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