std::codecvt

locale::facet		codecvt
codecvt_base

The codecvt standard facet is used to translate between different character encoding systems (such as multi-byte, UTF-16, ...)

codecvt objects are prevented to be locally constructed by having a protected destructor. Only those installed in locale objects should be used through mechanisms such as use_facet.


This template class has three template parameters, representing the internal character type, the external character type and the conversion state type. They are referred inside this entire reference as internT, externT and unshift, respectively:


The class defines three member aliases for these types: codecvt::intern_type, codecvt::extern_type and codecvt::state_type.

The internal character type is the base type used for translations, while the external character type is its counterpart in the translation. Translations can be performed in either direction with member functions codecvt::in and codecvt::out.

The conversion state type is the type of the object used to keep the state status in a particular translation, more generally used in variable-width character encodings. It is generally mbstate_t or some other compatible type.

Public members

It includes the following public member functions:

(constructor)

codecvt constructor (public member function)

Conversion functions:

in

Translate in characters (public member function)

out

Translate out characters (public member function)

unshift

Unshift translation state (public member function)

Character encoding properties:

always_noconv

Return noconv characteristics (public member function)

encoding

Return encoding width (public member function)

length

Return length of translated sequence (public member function)

max_length

Return max length of one character (public member function)

Along with the following public member types:

result

Operation result type (public member type)

intern_type

Internal character type (public member type)

extern_type

External character type (public member type)

state_type

Conversion state type (public member type)

Virtual protected members

The class defines the virtual protected members in charge of implementing the expected behavior of their corresponding public member functions:

do_always_noconv

Return noconv characteristics [virtual] (protected virtual member function)

do_encoding

Return encoding width [virtual] (protected virtual member function)

do_in

Translate in characters [virtual] (protected virtual member function)

do_length

Return length of translated sequence [virtual] (public member function)

do_max_length

Return max length of one character [virtual] (protected virtual member function)

do_out

Translate out characters [virtual] (protected virtual member function)

do_unshift

Unshift translation state [virtual] (protected virtual member function)

Including the class destructor

(destructor)

codecvt destructor (protected member function)

codecvt specialization: codecvt<char,char,mbstate_t>

Both the internal and external types are the narrow character type. This specialization performs no conversions at all

codecvt specialization: codecvt<wchar_t,char,mbstate_t>

Converts between the two fundamental character types using the system's native character set equivalences.