C# Keywords and Identifiers2 min read

It is important that before programming you should know the C# Keywords and Identifiers. You need to know that keywords cannot be used as identifiers and more.

C# Keywords

There are some predefined and reserved words that have special meanings to the compiler. These words are called Keywords. The meaning of the keywords in C# cannot be changed nor can you use them as an identifier. Some of the keywords that you see in a program are int, float, public, etc.

For Example:


There are 79 keywords in C#. All the keywords are written in lowercase.

List of C# keywords

abstractasbasebool
breakbytecasecatch
charcheckedclassconst
continuedecimaldefaultdelegate
dodoubleelseenum
eventexplicitexternfalse
finallyfixedfloatfor
foreachgotoifimplicit
inin (generic modifier)intinterface
internalislocklong
namespacenewnullobject
operatoroutout (generic modifier)override
paramsprivateprotectedpublic
readonlyrefreturnsbyte
sealedshortsizeofstackalloc
staticstringstructswitch
thisthrowtruetry
typeofuintulongunchecked
unsafeushortusingusing static
voidvolatilewhile 

Contextual Keywords

Aside from the above keywords, C# has 25 other keywords which are called contextual keywords. They have some specific meaning in a program. Unlike the above 79 regular keywords, contextual keywords are not reserved, they can be used as an identifier.

addaliasascending
asyncawaitdescending
dynamicfromget
globalgroupinto
joinletorderby
partial (type)partial (method)remove
selectsetvalue
varwhen (filter condition)where (generic type constraint)
yield  

You may go through each of them, Click Here.


C# Identifiers

Identifiers are nothing but the name assigned to the entities such as variables, functions in a program, Union, classes, etc. They are tokens that has a unique name so that they can be uniquely identified in a program.

Example: int number;, number being an identifier.

Rules for Naming an Identifiers:

  • Identifiers are case-sensitive that is uppercase and lowercase letters are distinct.
  • The first letter of identifiers must be a letter or underscore or symbols. After the first letter, you can use digits.
  • White spaces are not allowed.
  • A keyword cannot be used as an identifier.

Some valid and invalid identifiers:


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