mbstowcs - convert a multibyte string to a wide-character string

If dest is not NULL, the mbstowcs() function converts the multibyte string src to a wide-character string starting at dest.
At most n wide characters are written to dest.
The sequence of characters in the string src shall begin in the initial shift state.
The conversion can stop for three reasons:

An invalid multibyte sequence has been encountered.
In this case, (size_t) -1 is returned.
Wide characters non L'\0' have been stored at position n to dest.
In this case, the number of wide characters written to dest is returned, but the shift state at this point is lost.
The multibyte string has been completely converted, including the terminating null character L'\0'.
In this case, the number of wide characters written to dest, excluding the terminating null wide character, is returned.

The programmer must ensure that there is room for at least n wide characters at dest.

If dest is NULL, n is ignored, and the conversion proceeds as above, except that the converted wide characters are not written out to memory, and that no length limit exists.

In order to avoid the case 2 above, the programmer should make sure n is greater than or equal to:

... = mbstowcs(NULL,src,0) + 1;

Return Value

The mbstowcs() function returns the number of wide characters that make up the converted part of the wide-character string, not including the terminating null wide character.
If an invalid multibyte sequence was encountered, (size_t) -1 is returned.

Notes

The behavior of mbstowcs() depends on the LC_CTYPE category of the current locale.
The function mbstowcs() provides a better interface to the same functionality.

See example

See also: https://github.com/ClnViewer/LibWchar2/blob/master/test/test_mbstowcs.c

LibWchar2 information

Version: libwchar2 0.0.10

Date: Wed Aug 22 2018

Author: (c) PS 2018-2018

Manual author and license

Copyright: GNU Public License version 2. Manual license details