UTF8UTF16

UTF8UTF16 is not an official encoding defined by the Unicode Standard. In documentation and code, the term is sometimes used informally to refer to either UTF-8 or UTF-16, or to workflows that involve converting text between these two Unicode encodings. There is no single encoding named UTF8UTF16; the two are distinct formats with different characteristics and typical use cases.

UTF-8 encodes the entire set of Unicode code points as a variable-length sequence of 1 to 4 bytes. It is ASCII-compatible for the Basic Latin range, has no endianness, and is self-synchronizing, allowing for robust streaming. UTF-8 is widely used on the internet and in APIs because of its compatibility with existing byte-oriented systems.

UTF-16 represents code points using 16-bit units. Code points in the Basic Multilingual Plane fit in a single 16-bit unit, while supplementary characters are encoded as a pair of 16-bit units known as a surrogate pair. UTF-16 can be stored as big-endian or little-endian, and many platforms use a Byte Order Mark to indicate endianness. It is common on systems with strong affinity to 16-bit processing, such as Windows.

Converting between UTF-8 and UTF-16 involves decoding to Unicode code points and re-encoding. This requires handling surrogate pairs in UTF-16 and avoiding invalid sequences. Proper error handling is essential, as malformed input should not produce incorrect characters.

In practice, UTF-8 is often preferred for interchange and storage in cross-platform software, while UTF-16 remains common in certain platforms and APIs. The notion of UTF8UTF16 mostly arises from discussions about compatibility, data interchange, or the need to support both formats within a system. There is no separate standard format beyond the two encodings themselves.