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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.
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.
C# 3.0 introduced type inference, allowing the type specifier of a variable declaration to be replaced by the keyword var, if its actual type can be statically determined from the initializer. This reduces repetition, especially for types with multiple generic type-parameters , and adheres more closely to the DRY principle.
In Gosu, the ?: operator returns the right operand if the left is null as well. In C#, the null-conditional operator, ?. is referred to as the "Elvis operator", [10] but it does not perform the same function. Instead, the null-coalescing operator?? does. In ColdFusion and CFML, the Elvis operator was introduced using the ?: syntax.
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.
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.
A null coalescing operator is typically used to provide a default value to use when a variable is null -- and only when it is null, not zero or any other value (including false). The only way an operator in your above table can be considered a null coalescing operator is if it has Yes for the top row and No for every other row.
Null coalescing operators; Safe navigation operators; Modulo operators; Evaluation strategy; List of "Hello World" programs; ... NULL, nullptr: C# this: base [43 ...