C#: syntax

Syntax and other highlights of C#.

Identifiers

Identifiers – names of classes, methods, variables, etc. They must consist of Unicode characters and begin with a letter or underscore. Identifiers in C# are case sensitive. By convention, parameters, local variables, and private properties and methods are written in camel case (words are written together, without spaces or underscores, each new word except the first capitalized, for example, myVariavle), all other identifiers are in Pascal case style (same as camel case, only the first word is capitalized, e.g. MyClass).

Keywords

Keywords are compiler-reserved names that cannot be used as identifiers. Their complete list (76):

• 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
• while

If it is necessary to use a keyword as an identifier, this can be done by prefixing the keyword with the @ symbol, for example, @Class. In this case, the @ symbol will not be part of the identifier and @myVariable will be equivalent to myVariable.

There are also contextual keywords that, within a certain context, become keywords and cannot be used as identifiers, but outside their context they can be identifiers even without the @ symbol. These include:

• add
• ascending
• async
• await
• by
• descending
• dynamic
• equals
• from
• get
• global
• group
• in
• into
• join
• let
• on
• orderby
• partial
• remove
• select
• set
• value
• var
• where
• yield

Literals

Literals are the simplest pieces of data used in program code (for example, in the expression var myVariable = 12;, “12” is a literal).

Punctuators

Punctuators are used to delimit the structure of a program (for example, { } ;). Curly braces group multiple statements into a statement block. A semicolon separates non-block statements (a statement can be split across multiple lines).

Operators

Operators transform and combine expressions. Operators are denoted by symbols, for example, . ( ) * + =. The dot usually separates the fractional part in numeric literals (the decimal point) or is used as a delimiter for namespaces, classes, and their members. Parentheses are used when declaring and calling methods. An equals sign performs an assignment, a double equals sign performs a comparison.

Comments

Comments can be single-line or multi-line. A single line comment begins with a double slash and continues to the end of the line. Multiline starts with /* and ends with */.