In mathematics, a unary operation is an operation with only one operand (i.e. an operation with a single input). For instance, logical negation is a unary operation on truth values and squaring is a unary operation on the real numbers. Another unary operation is the factorial, n!. A unary operation on the set S is nothing but a function S → S.

Unary operators (called "monadic" in APL) are also used in programming languages. For example, in the C family of languages, the following operators are unary:

• Increment: ++x, x++
• Decrement: --x, x--
• Address: &x
• Indirection: *x
• Positive: +x
• Negative: -x
• One's complement: ~x
• Logical negation: !x
• Sizeof: sizeof x
• Sizeof: sizeof(type-name)
• Cast: (type-name) ''cast-expression

See also

• Binary operation
• Arity
• Operand
• Operator
• Operator (programming)

Elementary algebra | Programming constructs

Unární operace | Einstellige Verknüpfung | Unaarne tehe | Operación | Operazione unaria | פעולה יונארית | 手術 | Operacija | Unär operator | 运算