std::codecvt<InternT,ExternT,StateT>::unshift, do_unshift

Defined in header <locale>
result unshift( StateT& state,
                ExternT* to,
                ExternT* to_end,
                ExternT*& to_next) const;
virtual result do_unshift( StateT& state,
                           ExternT* to,
                           ExternT* to_end,
                           ExternT*& to_next) const;
1) public member function, calls the member function do_unshift of the most derived class.
2) if the encoding represented by this codecvt facet is state-dependent, and state represents a conversion state that is not the initial shift state, writes the characters necessary to return to the initial shift state. The characters are written to a character array whose first element is pointed to by to. No more than to_end-to characters are written. The parameter to_next is updated to point one past the last character written.

Return value

A value of type std::codecvt_base::result, indicating the success status as follows:

ok all necessary characters were written. state now represents initial shift state
partial not enough space in the output buffer. to_next == to_end
error unspecified error occurred
noconv the encoding is not state-dependent, no termination sequence necessary

The non-converting specialization std::codecvt<char, char, std::mbstate_t> always returns std::codecvt_base::noconv.


This function is called by std::basic_filebuf::close() and in other situations when finalizing a state-dependent multibyte character sequence.


See also

converts a wide character to its multibyte representation, given state
converts a string from InternT to ExternT, such as when writing to file
(virtual protected member function)

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