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.
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
//Valid way to write keyword
//Invalid way to write keyword
There are 79 keywords in C#. All the keywords are written in lowercase.
List of C# keywords
|in||in (generic modifier)||int||interface|
|operator||out||out (generic modifier)||override|
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.
|partial (type)||partial (method)||remove|
|var||when (filter condition)||where (generic type constraint)|
You may go through each of them, Click Here.
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.
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:
Number-2 //special character '-' is present.
3Sum //started with digit
int // int is a keyword