NULterminated

NULterminated refers to a string or character array in which the end of the string is indicated by a null character, typically the zero-valued byte '\0'. In this convention, the length of the string is not stored explicitly; instead, its end is determined by scanning forward until the first 0 byte is encountered.

NUL-terminated strings are most closely associated with the C programming language and the APIs derived from it. A character array or pointer to char is assumed to be terminated by a terminating zero, and standard functions such as those in the C standard library operate on these strings. This representation is common in C and C++ when interacting with legacy code and system interfaces.

Encoding and portability considerations: the terminator is a single zero byte, so ASCII and UTF-8 texts can be represented as NUL-terminated strings as long as embedded zero bytes are not part of the data. While the terminating byte enables simple memory layout and pointer-based length computation, it also means length calculation requires scanning the data and introduces potential safety risks if termination is corrupted or missing.

Limitations: embedded NUL bytes cannot appear within a NUL-terminated string, as any such zero would prematurely end the string. In modern software, alternative representations that store explicit lengths, such as length-prefixed strings or dynamic string types, are often preferred for safety and performance. In languages like C++, std::string maintains its own length and can be converted to a NUL-terminated C-style string via a helper method.

See also: null character, C string, C standard library, string handling in C.