Boolean expression

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In computer science, a Boolean expression is an expression in a programming language that produces a Boolean value when evaluated, i.e. one of true or false. A Boolean expression may be composed of a combination of the Boolean constants true or false, Boolean-typed variables, Boolean-valued operators, and Boolean-valued functions.

Boolean expressions correspond to propositional formulas in logic and are a special case of Boolean circuits.

Boolean operators[edit]

Most programming languages have the Boolean operators OR, AND and NOT; in C and some newer languages, these are represented by "||" (double pipe character), "&&" (double ampersand) and "!" (exclamation point) respectively, while the corresponding bitwise operations are represented by "|", "&" and "~" (tilde). In theoretical literature the symbols used are often "+" (plus), "·" (dot) and overbar, or "∨" (cup), "∧" (cap) and "¬" or "′" (prime).

Examples[edit]

  • The expression "5 > 3" is evaluated as true.
  • "5>=3" and "3<=5" are equivalent Boolean expressions, both of which are evaluated as true.
  • Of course, most Boolean expressions will contain at least one variable (X > 3), and often more (X > Y).

See also[edit]

External links[edit]

  • The Calculus of Logic, by George Boole, Cambridge and Dublin Mathematical Journal Vol. III (1848), pp. 183–98.