---
name: "wcsncpy"
section: "3p"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/wcsncpy/3p"
---

# wcsncpy(3p)

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

## PROLOG

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

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

## SYNOPSIS

```
#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*);

## DESCRIPTION

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.

## ERRORS

No errors are defined.

*The following sections are informative.*

## EXAMPLES

None.

## 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.

## RATIONALE

None.

## FUTURE DIRECTIONS

None.

## SEE ALSO

*strncpy()*, *wcscpy()*

The Base Definitions volume of POSIX.1‐2017, ***\<wchar.h\>***

## COPYRIGHT

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 .