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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".
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 ...
[1] [2] Similar syntax is used in other languages including Modula-2 [3] and Python. [4] In Pascal there is no return statement. Functions or procedures automatically return when reaching their last statement. The return value from a function is provided within the function by making an assignment to an identifier with the same name as the ...
While simple to implement, this representation has been prone to errors and performance problems. Null-termination has historically created security problems. [6] A NUL inserted into the middle of a string will truncate it unexpectedly. [7] A common bug was to not allocate the additional space for the NUL, so it was written over adjacent memory.
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.
In computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as an array index is within the bounds of the array (index checking).
var x1 = 0; // A global variable, because it is not in any function let x2 = 0; // Also global, this time because it is not in any block function f {var z = 'foxes', r = 'birds'; // 2 local variables m = 'fish'; // global, because it wasn't declared anywhere before function child {var r = 'monkeys'; // This variable is local and does not affect the "birds" r of the parent function. z ...
[2] [3] [4] It was created in 2008 by Jeff Atwood and Joel Spolsky. [5] [6] It features questions and answers on certain computer programming topics. [7] [8] [9] It was created to be a more open alternative to earlier question and answer websites such as Experts-Exchange.