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

PROLOG         top

       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         top

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

SYNOPSIS         top

       #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         top

       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

RETURN VALUE         top

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

       The strncpy() function shall return s1.

       No return values are reserved to indicate an error.

ERRORS         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top



       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

       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         top




SEE ALSO         top

       strcpy(3p), wcsncpy(3p)

       The Base Definitions volume of POSIX.1‐2008, string.h(0p)

COPYRIGHT         top

       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 .

       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 .

IEEE/The Open Group                 2013                         STRNCPY(3P)

Pages that refer to this page: string.h(0p)stpncpy(3p)strcpy(3p)wcsncpy(3p)