C Sharp syntaxThis article describes the syntax of the C# programming language. The features described are compatible with .NET Framework and Mono. An identifier is the name of an element in the code. It can contain letters, digits and underscores (_), and is case sensitive (FOO is different from foo). The language imposes the following restrictions on identifier names: They cannot start with a digit; They cannot start with a symbol, unless it is a keyword; They cannot contain more than 511 characters.
Double-ended queueIn computer science, a double-ended queue (abbreviated to deque, pronounced deck, like "cheque") is an abstract data type that generalizes a queue, for which elements can be added to or removed from either the front (head) or back (tail). It is also often called a head-tail linked list, though properly this refers to a specific data structure implementation of a deque (see below). Deque is sometimes written dequeue, but this use is generally deprecated in technical literature or technical writing because dequeue is also a verb meaning "to remove from a queue".
MetalanguageIn logic and linguistics, a metalanguage is a language used to describe another language, often called the object language. Expressions in a metalanguage are often distinguished from those in the object language by the use of italics, quotation marks, or writing on a separate line. The structure of sentences and phrases in a metalanguage can be described by a metasyntax. For example, to say that the word "noun" can be used as a noun in a sentence, one could write "noun" is a .
