PROLOG

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

NAME

       strlen, strnlen — get length of fixed size string

SYNOPSIS

       #include <string.h>

       size_t strlen(const char *s);
       size_t strnlen(const char *s, size_t maxlen);

DESCRIPTION

       For strlen(): The functionality described on this reference page is aligned with the ISO C
       standard. Any conflict between the requirements described here and the ISO C  standard  is
       unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard.

       The  strlen()  function shall compute the number of bytes in the string to which s points,
       not including the terminating NUL character.

       The strnlen() function shall compute the smaller of the number of bytes in  the  array  to
       which  s  points,  not including the terminating NUL character, or the value of the maxlen
       argument. The strnlen() function shall never examine more than maxlen bytes of  the  array
       pointed to by s.

RETURN VALUE

       The  strlen()  function shall return the length of s; no return value shall be reserved to
       indicate an error.

       The strnlen() function shall return an integer containing the smaller of either the length
       of the string pointed to by s or maxlen.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

   Getting String Lengths
       The following example sets the maximum length of key and data by using strlen() to get the
       lengths of those strings.

           #include <string.h>
           ...
           struct element {
               char *key;
               char *data;
           };
           ...
           char *key, *data;
           int len;

           *keylength = *datalength = 0;
           ...
           if ((len = strlen(key)) > *keylength)
               *keylength = len;
           if ((len = strlen(data)) > *datalength)
               *datalength = len;
           ...

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       wcslen()

       The Base Definitions volume of POSIX.1‐2008, <string.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  In  the  event  of  any
       discrepancy  between  this  version and the original IEEE and The Open Group Standard, the
       original IEEE and The Open Group Standard is the referee document. The  original  Standard
       can be obtained online at http://www.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .