cpp/locale/wstring convert/to bytes

Performs wide to multibyte conversion, using the facet supplied at construction.

@1@ Converts as if it was a string of length, to.

@2@ Converts the null-terminated wide character sequence beginning at the wide character pointed to by, to.

@3@ Converts the wide string to.

@4@ Converts the wide character sequence to.

In all cases, the conversion begins in initial shift state, unless non-initial starting state was provided to this constructor. The number of characters converted and the final value of the conversion state are remembered and can be accessed with state and converted

Return value
A object containing the results of the wide to multibyte conversion. If the conversion failed and there was a user-supplied byte-error string provided to the constructor of this, returns that byte-error string.

Exceptions
If this object was constructed without a user-supplied byte-error string, throws std on conversion failure.