From cppreference.com
The class text_encoding provides a mechanism for identifying character encodings. It is used to determine the
ordinary character literal encoding
of the translation environment at compile-time and the character encoding of the execution environment at runtime.
Each text_encoding object encapsulates a character encoding scheme, uniquely identified by an enumerator in
and a corresponding name represented by a null-terminated byte string. These can be accessed through the mib() and name() member functions, respectively. The determination of whether an object represents a character encoding scheme implemented in the translation or execution environment is implementation-defined.
The class text_encoding is a
type. The array object representing the corresponding name of the character encoding scheme is
the text_encoding object itself. The stored name is limited to a maximum of
characters excluding the null character '\0'.
The class supports both registered and non-registered character encodings. Registered encodings are those found in the
excluding the following character encodings:
NATS-DANO (33)
NATS-DANO-ADD (34).
In addition, the class provides access for registered character encodings to:
Primary name: The official name specified in the registry.
Aliases: An implementation-defined superset of aliases from the registry.
MIBenum value: A unique identifier for use in identifying coded character encodings.
Non-registered encodings can be represented with an enumerator id::other or id::unknown and a custom name.
A text_encoding object e whose MIBenum value is neither id::other nor id::unknown maintains the following invariants:
*e.name()!='\0' is true, and
e.mib()==std::text_encoding(e.name()).mib() is true.
Member types
represents the MIBenum value of the character encoding
(public member enum)
a
over aliases of the character encoding
(public member class)
Member constant
Name Value max_name_length
[static]
63
(public static member constant)Data members
Member Description std::text_encoding::idmib_(private)a MIBenum value with id::unknown as the default value
(exposition-only member object*)char[max_name_length+1]name_(private)a stored primary name
(exposition-only member object*)Member functions
Creation
constructs new text_encoding object
(public member function)
[static]
constructs a new text_encoding representing the
ordinary character literal encoding
(public static member function)
[static]
constructs a new text_encoding representing the implementation-defined character encoding scheme of the execution environment
(public static member function)
Observers
returns the MIBenum value of the current character encoding
(public member function)
returns the primary name of the current character encoding
(public member function)
returns a
over aliases of the current character encoding
(public member function)
[static]
checks the character encoding scheme of the execution environment with the specified MIB value
(public static member function)
Helpers
[static](private)
compares two alias names using
(exposition-only static member function*)
Non-member functions
Helper classes
Notes
When working with character encodings, it is important to note that the primary names or aliases of two distinct registered character encodings are not equivalent when compared using
as described by the Unicode Technical Standard.
For convenience, the enumerators of text_encoding::id are introduced as members of text_encoding and can be accessed directly. This means that text_encoding::ASCII and text_encoding::id::ASCII refer to the same entity.
It is recommended that the implementation should treat registered encodings as not interchangeable. Additionally, the primary name of a registered encoding should not be used to describe a similar but different non-registered encoding, unless there is a clear precedent for doing so.
macroValueStdFeature
(C++26)std::text_encodingExample
Run this code
#include<locale>#include<print>#include<text_encoding>intmain(){// literal encoding is known at compile-timeconstexprstd::text_encodingliteral_encoding=std::text_encoding::literal();// check for literal encodingstatic_assert(literal_encoding.mib()!=std::text_encoding::other&&literal_encoding.mib()!=std::text_encoding::unknown);// environment encoding is only known at runtimestd::text_encodingenv_encoding=std::text_encoding::environment();// associated encoding of the default localestd::text_encodinglocale_encoding=std::locale("").encoding();std::println("The literal encoding is {}",literal_encoding.name());std::println("The aliases of literal encoding:");for(constchar*alias_name:literal_encoding.aliases())std::println(" -> {}",alias_name);if(env_encoding==locale_encoding)std::println("Both environment and locale encodings are the same");std::println("The environment encoding is {}",env_encoding.name());std::println("The aliases of environment encoding:");for(constchar*alias_name:env_encoding.aliases())std::println(" -> {}",alias_name);}Possible output:
The literal encoding is UTF-8 The aliases of literal encoding: -> UTF-8 -> csUTF8 Both environment and locale encodings are the same The environment encoding is ANSI_X3.4-1968 The aliases of environment encoding: -> US-ASCII -> iso-ir-6 -> ANSI_X3.4-1968 -> ANSI_X3.4-1986 -> ISO_646.irv:1991 -> ISO646-US -> us -> IBM367 -> cp367 -> csASCII -> ASCII See also
set of polymorphic facets that encapsulate cultural differences
(class)