The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

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

#### SYNOPSIS

> ``#include <wchar.h>
> ``

> ``[CX] 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(): [CX] 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 [CX] 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

> [CX] 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

> XBD <wchar.h>

#### CHANGE HISTORY

> First released in Issue 4. Derived from the MSE working draft.

#### Issue 6

> The wcsncpy() prototype is updated for alignment with the ISO/IEC 9899:1999 standard.

#### Issue 7

> The wcpncpy() function is added from The Open Group Technical Standard, 2006, Extended API Set Part 1.

End of informative text.

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