std::codecvt::unshift, do_unshift

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Localizations library

Locales and facets
locale
use_facet	has_facet
Character classification
isspace isblank (C++11) iscntrl isupper islower isalpha	isdigit ispunct isxdigit isalnum isprint isgraph
Conversions
toupper tolower	wstring_convert (C++11) wbuffer_convert (C++11)
Facet category base classes
ctype_base codecvt_base messages_base	time_base money_base
Facet categories
ctype ctype<char> codecvt collate messages time_get time_put	num_get num_put numpunct money_get money_put moneypunct
Locale-specific facets
ctype_byname codecvt_byname messages_byname collate_byname	time_get_byname time_put_byname numpunct_byname moneypunct_byname
Code conversion facets
codecvt_utf8 (C++11) codecvt_utf16 (C++11)	codecvt_utf8_utf16 (C++11) codecvt_mode (C++11)
C locale
setlocale localeconv lconv	LC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME

 

std::codecvt

Member functions

codecvt::codecvt

codecvt::~codecvt

codecvt::outcodecvt::do_out

codecvt::incodecvt::do_in

codecvt::unshiftcodecvt::do_unshift

codecvt::encodingcodecvt::do_encoding

codecvt::always_noconvcodecvt::do_always_noconv

codecvt::lengthcodecvt::do_length

codecvt::max_lengthcodecvt::do_max_length

 

Defined in header <locale>
public: result unshift( StateT& state,                 ExternT* to,                 ExternT* to_end,                 ExternT*& to_next) const;	(1)
protected: virtual result do_unshift( StateT& state,                            ExternT* to,                            ExternT* to_end,                            ExternT*& to_next) const;	(2)

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

Notes

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

See also

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