In the context of computer programming, a token is a fundamental element of a programming language's syntax. It represents a single unit of meaningful information that cannot be further divided. Tokens are the building blocks of code and are used by compilers, interpreters, and other language processing systems to analyze and understand the program.
Tokens can represent various types of entities within a program, including:
- Keywords: Reserved words that have a predefined meaning in the programming language. Examples include
if,for, andwhile. - Identifiers: Names given to variables, functions, classes, or other program elements created by the programmer. They help identify and reference different entities within the code.
- Operators: Symbols used to perform mathematical or logical operations. Examples include
+,-,*,/, and=. - Literals: Literal values such as numbers, strings, or boolean values. Examples include
42,'Hello, World!', ortrue.
During the parsing and lexing phases of a program, tokens are identified and extracted from the source code. They serve as important markers for understanding the structure and meaning of the code, enabling the language processing systems to perform tasks like syntax highlighting, error detection, and generation of an abstract syntax tree.