The classtext_encoding provides a mechanism for identifying character encodings. It is used to determine theordinary character literal encoding of the translation environment at compile-time and the character encoding of the execution environment at runtime.

Eachtext_encoding object encapsulates acharacter encoding scheme, uniquely identified by an enumerator intext_encoding::id and a corresponding name represented by a null-terminated byte string. These can be accessed through themib() andname() 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 classtext_encoding is aTriviallyCopyable type. The array object representing the corresponding name of the character encoding scheme isnested within thetext_encoding object itself. The stored name is limited to a maximum ofmax_name_length characters excluding the null character'\0'.

The class supports both registered and non-registered character encodings. Registered encodings are those found in theIANA Character Sets Registry excluding the following character encodings:

• NATS-DANO (33)
• NATS-DANO-ADD (34).

In addition, the class provides access for registered character encodings to:

1. Primary name: The official name specified in the registry.
2. Aliases: An implementation-defined superset of aliases from the registry.
3. MIBenum value: A unique identifier for use in identifying coded character encodings.

Non-registered encodings can be represented with an enumeratorid::other orid::unknown and a custom name.

Atext_encoding objecte whose MIBenum value is neitherid::other norid::unknown maintains the following invariants:

• *e.name()!='\0' istrue, and
• e.mib()==std::text_encoding(e.name()).mib() istrue.

[edit]Member types

[edit]Member constant

[edit]Data members

[edit]Member functions

[edit]Non-member functions

[edit]Helper classes

[edit]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 usingCharset Alias Matching as described by the Unicode Technical Standard.

For convenience, the enumerators oftext_encoding::id are introduced as members oftext_encoding and can be accessed directly. This means thattext_encoding::ASCII andtext_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.

[edit]Example

#include <locale>#include <print>#include <text_encoding> int main(){// literal encoding is known at compile-timeconstexprstd::text_encoding literal_encoding= std::text_encoding::literal(); // check for literal encoding    static_assert(literal_encoding.mib()!= std::text_encoding::other&&                  literal_encoding.mib()!= std::text_encoding::unknown); // environment encoding is only known at runtimestd::text_encoding env_encoding= std::text_encoding::environment(); // associated encoding of the default localestd::text_encoding locale_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);}

The literal encoding is UTF-8The aliases of literal encoding: -> UTF-8 -> csUTF8Both environment and locale encodings are the sameThe environment encoding is ANSI_X3.4-1968The 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

[edit]See also

• In other languages

• Deutsch
• Español
• Français
• Italiano
• 日本語
• Português
• Русский
• 中文