STRLEN(3)                  POSIX Programmer's Manual                 STRLEN(3)



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

NNAAMMEE
       strlen, strnlen -- get length of fixed size string

SSYYNNOOPPSSIISS
       #include <string.h>

       size_t strlen(const char *_s);
       size_t strnlen(const char *_s, size_t _m_a_x_l_e_n);

DDEESSCCRRIIPPTTIIOONN
       For _s_t_r_l_e_n(): 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.1-2017 defers to the ISO C standard.

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

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

RREETTUURRNN VVAALLUUEE
       The _s_t_r_l_e_n() function shall return the length of _s; no return value
       shall be reserved to indicate an error.

       The _s_t_r_n_l_e_n() function shall return the number of bytes preceding the
       first null byte in the array to which _s points, if _s contains a null
       byte within the first _m_a_x_l_e_n bytes; otherwise, it shall return _m_a_x_l_e_n.

EERRRROORRSS
       No errors are defined.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
   GGeettttiinngg SSttrriinngg LLeennggtthhss
       The following example sets the maximum length of _k_e_y and _d_a_t_a by using
       _s_t_r_l_e_n() 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;
           ...

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       None.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _w_c_s_l_e_n()

       The Base Definitions volume of POSIX.1-2017, <<ssttrriinngg..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  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.opengroup.org/unix/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 .



IEEE/The Open Group                  2017                            STRLEN(3)
