---
name: "mbrtoc16"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/mbrtoc16"
---

# mbrtoc16(3)

convert a character to a wide-character code (restartable)

## NAME

**mbrtowc**, **mbrtoc16**, **mbrtoc32** – convert a character to a wide-character code (restartable)

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<wchar.h\>**

*size\_t*\

**mbrtowc**(*wchar\_t \* restrict pc*, *const char \* restrict s*, *size\_t n*, *mbstate\_t \* restrict ps*);

**#include \<uchar.h\>**

*size\_t*\

**mbrtoc16**(*char16\_t \* restrict pc*, *const char \* restrict s*, *size\_t n*, *mbstate\_t \* restrict ps*);

*size\_t*\

**mbrtoc32**(*char32\_t \* restrict pc*, *const char \* restrict s*, *size\_t n*, *mbstate\_t \* restrict ps*);

## DESCRIPTION

The **mbrtowc**(), **mbrtoc16**() and **mbrtoc32**() functions inspect at most *n* bytes pointed to by *s* to determine the number of bytes needed to complete the next multibyte character. If a character can be completed, and *pc* is not NULL, the wide character which is represented by *s* is stored in the *wchar\_t*, *char16\_t* or *char32\_t* it points to.

If *s* is NULL, these functions behave as if *pc* was NULL, *s* was an empty string ("") and *n* was 1.

The *mbstate\_t* argument, *ps*, is used to keep track of the shift state. If it is NULL, these functions use an internal, static *mbstate\_t* object, which is initialized to the initial conversion state at program startup.

As a single *char16\_t* is not large enough to represent certain multibyte characters, the **mbrtoc16**() function may need to be invoked multiple times to convert a single multibyte character sequence.

## RETURN VALUES

The **mbrtowc**(), **mbrtoc16**() and **mbrtoc32**() functions return:

- 0

  The next *n* or fewer bytes represent the null wide character (L'\\0').

- \>0

  The next *n* or fewer bytes represent a valid character, these functions return the number of bytes used to complete the multibyte character.

- (*size\_t*)-1

  An encoding error has occurred. The next *n* or fewer bytes do not contribute to a valid multibyte character.

- (*size\_t*)-2

  The next *n* contribute to, but do not complete, a valid multibyte character sequence, and all *n* bytes have been processed.

The **mbrtoc16**() function also returns:

- (*size\_t*)-3

  The next character resulting from a previous call has been stored. No bytes from the input have been consumed.

## ERRORS

The **mbrtowc**(), **mbrtoc16**() and **mbrtoc32**() functions will fail if:

- \[EILSEQ\]

  An invalid multibyte sequence was detected.

- \[EINVAL\]

  The conversion state is invalid.

## SEE ALSO

[mbtowc(3)](/mbtowc/3.md), [multibyte(3)](/multibyte/3.md), [setlocale(3)](/setlocale/3.md), [wcrtomb(3)](/wcrtomb/3.md)

## STANDARDS

The **mbrtowc**(), **mbrtoc16**() and **mbrtoc32**() functions conform to ISO/IEC 9899:2011 (“ISO C11”).