# Boolean expression

In computer science, a Boolean expression is an expression used in programming languages that produces a Boolean value when evaluated. A Boolean value is either 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

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 the mathematical literature the symbols used are often "+" (plus), "·" (dot) and overbar, or "∨" (vel), "∧" (et) and "¬" (not) or "′" (prime).

## Examples

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