C Sharp syntax

This 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. Identifier names may be prefixed by an at sign (@), but this is insignificant; @name is the same identifier as name. Microsoft has published naming conventions for identifiers in C#, which recommends the use of PascalCase for the names of types and most type members, and CamelCase for variables and for private or internal fields. However, these naming conventions are not enforced in the language. Keywords are predefined reserved words with special syntactic meaning. The language has two types of keyword — contextual and reserved. The reserved keywords such as false or byte may only be used as keywords. The contextual keywords such as where or from are only treated as keywords in certain situations. If an identifier is needed which would be the same as a reserved keyword, it may be prefixed by an at sign to distinguish it. For example, @out is interpreted as an identifier, whereas out as a keyword. This syntax facilitates reuse of .NET code written in other languages. The following C# keywords are reserved words: abstract as base bool break byte case catch char checked class const continue decimal default delegate do double else enum event explicit extern false finally fixed float for foreach goto if implicit in int interface internal is lock long namespace new null object operator out override params private protected public readonly ref return sbyte sealed short sizeof stackalloc static string struct switch this throw true try typeof uint ulong unchecked unsafe ushort using virtual void volatile while A contextual keyword is used to provide a specific meaning in the code, but it is not a reserved word in C#.