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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 ...
If n is greater than the length of the string then most implementations return the whole string (exceptions exist – see code examples). Note that for variable-length encodings such as UTF-8 , UTF-16 or Shift-JIS , it can be necessary to remove string positions at the end, in order to avoid invalid strings.
In JavaScript an object is a mapping from property names to values—that is, an associative array with one caveat: the keys of an object must be either a string or a symbol (native objects and primitives implicitly converted to a string keys are allowed). Objects also include one feature unrelated to associative arrays: an object has a ...
A property, in some object-oriented programming languages, is a special sort of class member, intermediate in functionality between a field (or data member) and a method.The syntax for reading and writing of properties is like for fields, but property reads and writes are (usually) translated to 'getter' and 'setter' method calls.
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 some of these languages an extra keyword is used to declare no return value; for example void in C, C++ and C#. In some languages, such as Python, the difference is whether the body contains a return statement with a value, and a particular callable may return with or without a value based on control flow.
On the contrary, the actual objects in some cases can be changed. In the following example, object String is not changed. Object of class 'a' is changed. In C#, it is possible to enforce a reference with the ref keyword, similar to C++ and in a sense to C. This feature of C# is particularly useful when one wants to create a method that returns ...
XPath is an example of a path expression language. In concurrency control, path expressions are a mechanism for expressing permitted sequences of execution. For example, a path expression like "{read}, write" might specify that either multiple simultaneous executions of read or a single execution of write but not both are allowed at any point ...