C# Keywords

Keywords are predefined, reserved identifiers that have special meanings to the compiler. They cannot be used as identifiers in your program unless they include @ as a prefix. For example, @if is a valid identifier, but if is not because if is a keyword.

The first table in this topic lists keywords that are reserved identifiers in any part of a C# program. The second table in this topic lists the contextual keywords in C#. Contextual keywords have special meaning only in a limited program context and can be used as identifiers outside that context. Generally, as new keywords are added to the C# language, they are added as contextual keywords in order to avoid breaking programs written in earlier versions.

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 in (generic modifier) int interface
internal is lock long
namespace new null object
operator out out (generic modifier) 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 using static
virtual void volatile while

Contextual Keywords

A contextual keyword is used to provide a specific meaning in the code, but it is not a reserved word in C#. Some contextual keywords, such as partial and where, have special meanings in two or more contexts.

add alias ascending
async await descending
dynamic from get
global group into
join let nameof
orderby partial (type) partial (method)
remove select set
value var when (filter condition)
where (generic type constraint) where (query clause) yield

See Also

C# Reference
C# Programming Guide