std::text_encoding

Since C++26

Header: <text_encoding>

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.

# Declarations

struct text_encoding;

(since C++26)

# 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 Charset Alias Matching 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.

# Example

#include <locale>
#include <print>
#include <text_encoding>
 
int main()
{
    // literal encoding is known at compile-time
    constexpr std::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 runtime
    std::text_encoding env_encoding = std::text_encoding::environment();
 
    // associated encoding of the default locale
    std::text_encoding locale_encoding = std::locale("").encoding();
 
    std::println("The literal encoding is {}", literal_encoding.name());
    std::println("The aliases of literal encoding:");
    for (const char* 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 (const char* alias_name : env_encoding.aliases())
        std::println(" -> {}", alias_name);
}

# See also

locale