wcsncpy - Man Page

copy a fixed-size wide-character string, returning a pointer to its end


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.


#include <wchar.h>

wchar_t *wcpncpy(wchar_t restrict *ws1, const wchar_t *restrict ws2,
    size_t n);
wchar_t *wcsncpy(wchar_t *restrict ws1, const wchar_t *restrict ws2,
    size_t n);


For wcsncpy(): 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 wcpncpy() and wcsncpy() functions shall copy not more than n wide-character codes (wide-character codes that follow a null wide-character code are not copied) from the array pointed to by ws2 to the array pointed to by ws1. If copying takes place between objects that overlap, the behavior is undefined.

If the array pointed to by ws2 is a wide-character string that is shorter than n wide-character codes, null wide-character codes shall be appended to the copy in the array pointed to by ws1, until n wide-character codes in all are written.

Return Value

If any null wide-character codes were written into the destination, the wcpncpy() function shall return the address of the first such null wide-character code. Otherwise, it shall return &ws1[n].

The wcsncpy() function shall return ws1.

No return values are reserved to indicate an error.


No errors are defined.

The following sections are informative.



Application Usage

If there is no null wide-character code in the first n wide-character codes of the array pointed to by ws2, the result is not null-terminated.



Future Directions


See Also

strncpy(), wcscpy()

The Base Definitions volume of POSIX.1-2017, <wchar.h>

Referenced By

strncpy(3p), wchar.h(0p), wcscpy(3p).

2017 IEEE/The Open Group POSIX Programmer's Manual