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In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (null) behavior.The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" [1] and later in the Pattern Languages of Program Design book series as "Null Object".
A C# namespace provides the same level of code isolation as a Java package or a C++ namespace, with very similar rules and features to a package. Namespaces can be imported with the "using" syntax. Namespaces can be imported with the "using" syntax.
Number of UTF-16 code units: Java (string-length string) Scheme (length string) Common Lisp, ISLISP (count string) Clojure: String.length string: OCaml: size string: Standard ML: length string: Number of Unicode code points Haskell: string.length: Number of UTF-16 code units Objective-C (NSString * only) string.characters.count: Number of ...
In computer programming, a declaration is a language construct specifying identifier properties: it declares a word's (identifier's) meaning. [1] Declarations are most commonly used for functions, variables, constants, and classes, but can also be used for other entities such as enumerations and type definitions. [1]
When a string appears literally in source code, it is known as a string literal or an anonymous string. [ 1 ] In formal languages , which are used in mathematical logic and theoretical computer science , a string is a finite sequence of symbols that are chosen from a set called an alphabet .
The empty string should not be confused with the empty language ∅, which is a formal language (i.e. a set of strings) that contains no strings, not even the empty string. The empty string has several properties: |ε| = 0. Its string length is zero. ε ⋅ s = s ⋅ ε = s. The empty string is the identity element of the concatenation operation
In some programming language environments (at least one proprietary Lisp implementation, for example), [citation needed] the value used as the null pointer (called nil in Lisp) may actually be a pointer to a block of internal data useful to the implementation (but not explicitly reachable from user programs), thus allowing the same register to be used as a useful constant and a quick way of ...
The null coalescing operator is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, such as (in alphabetical order): C# [1] since version 2.0, [2] Dart [3] since version 1.12.0, [4] PHP since version 7.0.0, [5] Perl since version 5.10 as logical defined-or, [6] PowerShell since 7.0.0, [7] and Swift [8] as nil-coalescing operator.