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# std::c16rtomb

From cppreference.com
< cpp‎ | string‎ | multibyte

Defined in header `<cuchar>` |  |
std::size_t c16rtomb( char* s, char16_t c16, std::mbstate_t* ps ); |  | (since C++11)

Converts a 16-bit wide character to narrow multibyte character.

If `s` is not a null pointer, the function determines the number of bytes necessary to store the multibyte character representation of `c16` (including any shift sequences), and stores the multibyte character representation in the character array whose first element is pointed to by `s`. At most MB_CUR_MAX bytes can be written by this function.

If `s` is a null pointer, the call is equivalent to std::c16rtomb(buf, u'\0', ps) for some internal buffer `buf`.

If c16 is the null wide character u'\0', a null byte is stored, preceded by any shift sequence necessary to restore the initial shift state and the conversion state parameter *ps is updated to represent the initial shift state.

If the macro __STDC_UTF_16__ is defined, the 16-bit encoding used by this function is UTF-16, otherwise it is implementation-defined. In any case, the multibyte encoding used by this function is specified by the currently active C locale.

### [edit] Parameters

s | - | pointer to narrow character array where the multibyte character will be stored
c16 | - | the 16-bit character to convert
ps | - | pointer to the conversion state object used when interpreting the multibyte string

### [edit] Return value

On success, returns the number of bytes (including any shift sequences) written to the character array whose first element is pointed to by `s`. This value may be ​0​, e.g. when processing the first char16_t in a surrogate pair.

On failure (if c16 is not a valid 16-bit character), returns -1, stores EILSEQ in errno, and leaves *ps in unspecified state.

### [edit] See also

mbrtoc16 (C++11) | generate the next 16-bit wide character from a narrow multibyte string (function) [edit]
do_out [virtual] | converts a string from internT to externT, such as when writing to file (virtual protected member function of `std::codecvt`) [edit]
C documentation for c16rtomb

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