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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 many contexts, including C++, C# and Java, an object is created via special syntax like new typename(). In C++, that provides manual memory management, an object is destroyed via the delete keyword. In C# and Java, with no explicit destruction syntax, the garbage collector destroys unused objects automatically and non-deterministically.
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.
When an object value is declared with no argument list (e.g.: MyClass x;) or allocated dynamically with no argument list (e.g.: new MyClass; or new MyClass();), the default constructor of MyClass is used to initialize the object. When an array of objects is declared, e.g. MyClass x[10];; or allocated dynamically, e.g. new MyClass [10].
The lazy initialization technique allows us to do this in just O(m) operations, rather than spending O(m+n) operations to first initialize all array cells. The technique is simply to allocate a table V storing the pairs ( k i , v i ) in some arbitrary order, and to write for each i in the cell T [ k i ] the position in V where key k i is stored ...
There is also a variable, firstNode which always points to the first node in the list, or is null for an empty list. record Node { data; // The data being stored in the node Node next // A reference [2] to the next node, null for last node } record List { Node firstNode // points to first node of list; null for empty list}
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The initializer list is required if you have const or reference type data members, or members that do not have parameterless constructor logic. Assignments occur according to the order in which data members are declared (even if the order in the initializer list is different). [3]