u0000

U+0000, commonly referred to as NULL, is the first code point in the Unicode standard and corresponds to the value 0 in ASCII. It is defined as a control character and has no visible glyph, making it non-printable in typical text displays.

Classification and name: In Unicode, U+0000 is a C0 control character with the general category Cc. The official name is NULL, and it is part of the Basic Latin block. It is not assigned a graphic representation in standard fonts and is usually rendered as a non-printing symbol or left invisible.

Encoding representations: In UTF-8, U+0000 is encoded as a single byte 0x00. In UTF-16, it is encoded as 0x0000 (with endianness determined by the surrounding encoding). In UTF-32, it is 0x00000000. These encodings preserve the code point’s value as a non-printable control character.

Usage in computing: The NUL character is widely used as the string terminator in C, C++, and many related languages, marking the end of a character sequence. It can also serve as a padding byte or delimiter in certain binary formats and network protocols. In text processing, its presence is typically not intended to display as a character.

Impact and considerations: Correct handling of U+0000 is essential for binary input/output, string processing, and data interoperability. Some languages and tools treat NUL as a terminator or may reject or strip it from text streams, while others preserve it as data. Awareness of its non-printable nature helps prevent parsing or security issues in software.

See also: Unicode code points, NUL, ASCII, C0 control codes, NULL character.