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C# is a language in which the null object pattern can be properly implemented. This example shows animal objects that display sounds and a NullAnimal instance used in place of the C# null keyword. The null object provides consistent behaviour and prevents a runtime null reference exception that would occur if the C# null keyword were used instead.
C# 6.0 and above have ?., the null-conditional member access operator (which is also called the Elvis operator by Microsoft and is not to be confused with the general usage of the term Elvis operator, whose equivalent in C# is ??, the null coalescing operator) and ?[], the null-conditional element access operator, which performs a null-safe call of an indexer get accessor.
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 Ada, the null statement serves as a NOP. [13] As the syntax forbids that control statements or functions be empty, the null statement must be used to specify that no action is required. (Thus, if the programmer forgets to write a sequence of statements, the program will fail to compile.)
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
As a precursor to the lambda functions introduced in C# 3.0, C#2.0 added anonymous delegates. These provide closure-like functionality to C#. [3] Code inside the body of an anonymous delegate has full read/write access to local variables, method parameters, and class members in scope of the delegate, excepting out and ref parameters. For example:-
This is a feature of C# 9.0. Similar to in scripting languages, top-level statements removes the ceremony of having to declare the Program class with a Main method. Instead, statements can be written directly in one specific file, and that file will be the entry point of the program. Code in other files will still have to be defined in classes.
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 ...