Section: POSIX Programmer's Manual (3P)
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.
--- copy fixed length string, returning a pointer to the array end
char *stpncpy(char *restrict s1, const char *restrict s2, size_t n);
char *strncpy(char *restrict s1, const char *restrict s2, size_t 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.1-2008 defers to the ISO C standard.
functions shall copy not more than
bytes (bytes that follow a NUL character are not copied) from the array
pointed to by
to the array pointed to by
If the array pointed to by
is a string that is shorter than
bytes, NUL characters shall be appended to the copy in the array
pointed to by
bytes in all are written.
If copying takes place between objects that overlap, the behavior is
If a NUL character is written to the destination, the
function shall return the address of the first such NUL character.
Otherwise, it shall return
function shall return
No return values are reserved to indicate an error.
No errors are defined.
The following sections are informative.
Applications must provide the space in
bytes to be transferred, as well as ensure that the
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
bytes of the array pointed to by
the result is not null-terminated.
The Base Definitions volume of POSIX.1-2008,
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
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