Karl Jones: Created page with "In computing, '''null''' has different definitions in different contexts. The general idea is "nonexistence". == Definition == * Null (SQL), a special marker and ..."

2016-09-23T00:52:10Z

Created page with "In computing, '''null''' has different definitions in different contexts. The general idea is "nonexistence". == Definition == * Null (SQL), a special marker and ..."

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In [[computing]], '''null''' has different definitions in different contexts.

The general idea is "nonexistence".

== Definition ==

* [[Null (SQL)]], a special marker and [[keyword]] in [[SQL]] indicating that something has no value.
* [[Null character]], the zero-valued ASCII character, also designated by NUL, often used as a terminator, separator or filler. This symbol has no visual representation.
* [[Null device]], a special computer file that discards all data written to it
* [[Null modem]], a specially wired serial communications cable
* [[Null Object pattern]], a software design pattern using an object with defined neutral behavior
* [[Null pointer]] (sometimes written NULL, nil, or None), used in computer programming for an uninitialized, undefined, empty, or meaningless value
* [[Null string]], the unique string of length zero (in computer science and formal language theory)
* [[Null-terminated string]], a character string of which the length is determined by the first null-character (in programming language C and related languages)
* [[Nullable type]], a feature of some statically-typed programming languages which allows a data type to be set to the special value NULL

== See also ==

== External links ==

* [https://www.infoq.com/presentations/Null-References-The-Billion-Dollar-Mistake-Tony-Hoare Null References: The Billion Dollar Mistake] by [[Tony Hoare]]

Null (computing) - Revision history

Karl Jones: Created page with "In computing, '''null''' has different definitions in different contexts. The general idea is "nonexistence". == Definition == * Null (SQL), a special marker and ..."