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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".
In object-oriented programming, the safe navigation operator (also known as optional chaining operator, safe call operator, null-conditional operator, null-propagation operator) is a binary operator that returns null if its first argument is null; otherwise it performs a dereferencing operation as specified by the second argument (typically an ...
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type.In statically typed languages, a nullable type is an option type, [citation needed] while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null ...
In programming languages (especially functional programming languages) and type theory, an option type or maybe type is a polymorphic type that represents encapsulation of an optional value; e.g., it is used as the return type of functions which may or may not return a meaningful value when they are applied.
In Python, there is a type called NoneType which allows the single value of None. In Python's optional static type annotations, this type is represented as None. [1] In Swift, the unit type is called Void or and its only value is also (), reflecting the 0-tuple interpretation. In Java, the unit type is called Void and its only value is null.
Control options for the current connection and list of hop-by-hop response fields. [13] Must not be used with HTTP/2. [14] Connection: close: Permanent RFC 9110: Content-Disposition [51] An opportunity to raise a "File Download" dialogue box for a known MIME type with binary format or suggest a filename for dynamic content.
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types ...
If the default argument is explicitly given, then that value is used if it is not provided by the caller. If the default argument is implicit (sometimes by using a keyword such as Optional) then the language provides a well-known value (such as null, Empty, zero, an empty string, etc.) if a value is not provided by the caller. PowerShell example: