literals

In programming languages, a literal is a notation for a fixed value written directly in source code. Literals denote values that are constant and do not require evaluation, unlike expressions or variables whose values may change at runtime. They are typically parsed by the language’s lexer and converted into the corresponding runtime representation.

Numeric literals express numbers. Integer literals may be decimal, binary, octal, or hexadecimal, and may include digit separators for readability. Floating-point literals express real numbers and can use decimal notation or scientific notation (for example, 3.14 or 1e-9). Some languages also support suffixes to denote type or precision.

Character literals represent single characters, usually placed in quotes. They may support escape sequences such as newline, tab, or quote characters. In many languages, characters constitute a separate type from strings.

String literals define sequences of characters and are enclosed in quotes. They may support escape sequences, and some languages offer multi-line strings or raw strings that ignore escapes.

Boolean literals represent truth values, commonly true and false. Null-like literals denote absence of a value, such as null, nil, or None, depending on the language.

Composite literals describe data structures that are written inline, such as arrays or lists, dictionaries or maps, and tuples. These literals allow the inline construction of complex data values.

Literals provide constants that improve clarity and performance, since their values are known at source time. They may be immutable or immutable by convention, with differing rules across languages.