pattern null

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• Null Object pattern — Null object redirects here. For the concept in category theory, see Initial object. In object oriented computer programming, a Null Object is an object with defined neutral ( null ) behavior. The Null Object design pattern describes the uses of… …   Wikipedia

• Null (SQL) — The Greek lowercase omega (ω) character is used to represent Null in database theory. Null is a special marker used in Structured Query Language (SQL) to indicate that a data value does not exist in the database. Introduced by the creator of the… …   Wikipedia

• Null character — For other uses, see Null symbol. The null character (also null terminator), abbreviated NUL, is a control character with the value zero.[1] [2] It is present in many character sets, including ISO/IEC 646 (or ASCII), the C0 control code, the… …   Wikipedia

• Null function — Not to be confused with identity function or empty function. In computer science, a null function (or null operator) is subroutine that returns no data values and leaves the program state unchanged. When it is part of the instruction set of… …   Wikipedia

• Pattern theory — Pattern theory, formulated by Ulf Grenander, is a mathematical formalism to describe knowledge of the world as patterns. It differs from other approaches to artificial intelligence in that it does not begin by prescribing algorithms and machinery …   Wikipedia

• Null — may refer to: Contents 1 In computing 2 In art 3 In mathematics 4 In science 5 People …   Wikipedia

• Null fill — is used in radio antenna systems which are located on mountains or tall towers, to prevent too much of the signal from overshooting the nearest part of intended coverage area. Phasing is used between antenna elements to take power away from the… …   Wikipedia

• Null (physics) — In physics a null is a point in a field where the field quantity is zero as the result of two or more opposing quantities completely cancelling each other. The field may be scalar, vector or tensor in nature. Common situations where nulls arise… …   Wikipedia

• Null (radio) — Yagi Uda antenna polar pattern showing pattern of alternating lobes and nulls In radio electronics, a null is an area or vector in an antenna s radiation pattern where the signal cancels out almost entirely. This can be an advantage, as nulls in… …   Wikipedia

• Null corrector — Testing a spherical mirror using an interferometer. All surfaces in the tester are either flat or spherical, so the tester itself is fairly easy to fabricate and test. This setup can test a spherical mirror of any size since the wavefront is… …   Wikipedia

• Null coalescing operator — The null coalescing operator (or Logical Defined Or Operator) is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, including C#,[1] and Perl as of version 5.10.[2] In Scheme, boolean …   Wikipedia