A special value used in several languages to represent the thing referred to by an uninitialised pointer.


A special value that may be stored in some database columns to represent an unknown, missing, not applicable, or undefined value. Nulls are treated completely differently from ordinary values when evaluating SQL expressions and there are several SQL constructs for dealing with nulls.

Last updated: 2003-06-17



A description of an operator or function which takes no arguments, e.g. a function that returns the current time.

"Nullary" is part of the unary, binary, ternary sequence, and is more common than its synonym niladic.

Last updated: 2001-02-25

null modem

<communications, hardware>

A cable, especially an EIA-232 cable, for connecting serial ports on two computers directly, rather than via modems. Since, according to the specification, both computers should transmit on pin three of their EIA-232 connectors and receive on pin two, a null modem cable needs to connect one computer's pin two to the other's pin three and vice versa. It also needs to have male connectors at both ends (again, according to the specification).

Last updated: 1996-05-17

null-terminated multibyte string


(NTMBS) (Defined in the ANSI C++ draft)

[Different from null-terminated string?]

Last updated: 1995-10-02

Nearby terms:

nudenukenullnullarynull modemnull-terminated multibyte string

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