NAME¶

std::codecvt::unshift,do_unshift - std::codecvt::unshift,do_unshift

Synopsis¶

Defined in header <locale>
public:

result unshift( StateT& state, ExternT* to, ExternT* to_end, (1)

ExternT*& to_next ) const;
protected:

virtual result do_unshift( StateT& state, ExternT* to, ExternT* to_end, (2)

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 an unspecified error has occurred
noconv the encoding is not state-dependent, no termination sequence necessary

Notes¶

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

Example¶

This section is incomplete
Reason: no example

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
std::codecvt<wchar_t, char,
LWG 305 C++98 std::mbstate_t>::do_unshift not required
was required not to write any character
the meaning of returning partial was 'more corrected to
LWG 380 C++98 characters need to indicating
be supplied to complete termination', but no insufficient buffer
character is supplied space
state is required to
LWG 381 C++98 state was not required to be valid, and be valid, and
error is returned if state is invalid returning error
indicates an error
std::codecvt<char, char,
LWG 664 C++98 std::mbstate_t>::do_unshift not required
was required not to write any character
std::codecvt<char, char,
LWG 665 C++98 std::mbstate_t>::do_unshift not required
was required to return noconv

See also¶

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

Category:¶

* Todo no example