Token

What is a token in the C# programming language? A token is a specific part of a C# program. The specification defines a token using the C# grammar.

Tokens are generally any unit that is not whitespace or a comment. They are part of the text of a program. We examine tokens at the level of the C# language.

Example

Let us explore the concept of tokens by looking at this C# program. We see the program and then break it up into individual tokens.

class Program
{
    static void Main()
    {
        int test = 2;
        float item = 5.5f;
        char unit = 'e';
        string basic = "c#";
    }
}
class
Program
"{"
static
void
Main
(
)
"{"
int
test
=
2
;
float
item
=
5.5f
;
char
unit
=
'e'
;
string
basic
=
"c#"
;
"}"
"}"
identifier:

Identifiers are arbitrary names in your C# program.
This includes Program, Main, test, item, unit and basic.

keyword:

Many keywords are reserved by the C# language.
These include class, static, void, int, float, char and string.

integer-literal:
real-literal:
character-literal:
string-literal:

Literals are constant values you can use in your program.
These include 2, 5.5f, 'e' and "c#".
Literals include the enclosing quotation marks.
For the literal 5.5f, the numeric suffix is included in the literal.
This is a real-literal.

operator-or-punctuator:

These are characters in your program that are part of the scope
structure, or assignment and arithmetic statements.
Some operators, such as && are considered a single token.
The characters () are separate tokens.

Specification

For more material like this on the C# language, the specification is available. This material was adapted from page 61 of the C# annotated specification.

We now know what a token is in the C# language. This can be helpful in understanding how the language is parsed—and how to fix compile-time errors.

Any time you see more closely how the compiler approaches a language, you gain insight into how it should be used. This description provides insight into how the C# compiler views programs.