STRNCPY(3P)						     POSIX Programmer's Manual						       STRNCPY(3P)

PROLOG

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

NAME

       stpncpy, strncpy -- copy fixed length string, returning a pointer to the array end

SYNOPSIS

       #include <string.h>

       char *stpncpy(char *restrict s1, const char *restrict s2, size_t n);
       char *strncpy(char *restrict s1, const char *restrict s2, size_t n);

DESCRIPTION

       For strncpy(): 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  stpncpy()  and  strncpy() functions shall copy not more than n bytes (bytes that follow a NUL character are not copied) from the array
       pointed to by s2 to the array pointed to by s1.

       If the array pointed to by s2 is a string that is shorter than n bytes, NUL characters shall be appended to the copy in the  array  pointed
       to by s1, until n bytes in all are written.

       If copying takes place between objects that overlap, the behavior is undefined.

RETURN VALUE

       If  a NUL character is written to the destination, the stpncpy() function shall return the address of the first such NUL character.  Other-
       wise, it shall return &s1[n].

       The strncpy() function shall return s1.

       No return values are reserved to indicate an error.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Applications must provide the space in s1 for the n bytes to be transferred, as well as ensure that the s2 and s1 arrays do not overlap.

       Character movement is performed differently in different implementations. Thus, overlapping moves may yield surprises.

       If there is no NUL character byte in the first n bytes of the array pointed to by s2, the result is not null-terminated.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       strcpy(), wcsncpy()

       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 Technol-
       ogy  --	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 Stan-
       dard 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 .

IEEE
/The Open Group						       2013							       STRNCPY(3P)