WCSRTOMBS(3) | Library Functions Manual | WCSRTOMBS(3)

# NAME

`wcsrtombs`, `wcsnrtombs` —
converts a wide-character string to a multibyte character string (restartable)

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

`#include <wchar.h>`

size_t
`wcsrtombs`(char * restrict s, const wchar_t ** restrict pwcs, size_t n, mbstate_t * restrict ps);

size_t
`wcsnrtombs`(char * restrict s, const wchar_t ** restrict pwcs, size_t nwc, size_t n, mbstat_t * restrict ps);

# DESCRIPTION

The `wcsrtombs`() function converts the NUL-terminated wide-character string indirectly pointed to by pwcs to the corresponding multibyte character string, and stores it in the array pointed to by s. The conversion stops due to the following reasons:

- The conversion reaches a NUL wide character. In this case, the NUL wide character is also converted.
- The `wcsrtombs`() has already stored n bytes in the array pointed to by s.
- The conversion encounters an invalid character.

Each character will be converted as if wcrtomb(3) is continuously called, except the internal state of wcrtomb(3) will not be affected.

After conversion, if s is not a NULL pointer, the pointer object pointed to by pwcs is a NULL pointer (if the conversion is stopped due to reaching a NUL wide character) or points to the first byte of the character just after the last character converted.

If s is not a NULL pointer and the conversion is stopped due to reaching a NUL wide character, `wcsrtombs`() places the state object pointed to by ps to an initial state after the conversion is taken place.

The behavior of `wcsrtombs`() is affected by the `LC_CTYPE` category of the current locale.

These are the special cases:

`s == NULL`
  `wcsrtombs`() returns the number of bytes to store the whole multibyte character string corresponding to the wide-character string pointed to by pwcs, not including the terminating NUL byte. In this case, n is ignored.
`pwcs == NULL || *pwcs == NULL`
  Undefined (may cause the program to crash).
`ps == NULL`
  `wcsrtombs`() uses its own internal state object to keep the conversion state, instead of ps mentioned in this manual page.

  Calling any other functions in Standard C Library (libc, -lc) never changes the internal state of `wcsrtombs`(), which is initialized at startup time of the program.

The `wcsnrtombs`() function behaves identically to `wcsrtombs`(), except that the conversion stops after reading at most nwc characters from the buffer pointed to by pwcs.

# RETURN VALUES

The `wcsrtombs`() and `wcsnrtombs`() functions return:

`0`, or positive
  Number of bytes stored in the array pointed to by s, except for a NUL byte. There are no cases that the value returned is greater than n (unless s is a NULL pointer). If the return value is equal to n, the string pointed to by s will not be NUL-terminated.
`(size_t)-1`
  pwcs points to a string containing an invalid wide character. The `wcsrtombs`() also sets errno to indicate the error.

# ERRORS

The `wcsrtombs`() and `wcsnrtombs`() functions may fail with the following errors:

[`EILSEQ`]
  pwcs points to a string containing an invalid wide character.
[`EINVAL`]
  ps points to an invalid or uninitialized mbstate_t object.

# SEE ALSO

setlocale(3), wcrtomb(3), wcstombs(3)

# STANDARDS

The `wcsrtombs`() function conforms to ANSI X3.159-1989 (“ANSI C89”). The `restrict` qualifier was added by ISO/IEC 9899:1999 (“ISO C99”).

The `wcsnrtombs`() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

August 27, 2017 | NetBSD 9.5