unary operator
An operator that requires only one operand. The unary operator appears before
the operand. In an expression, unary operators always have higher precedence
than binary operators. In 4GL, examples include logical NOT, unary plus (+), and
unary minus (-). 4GL associates most unary operators from right-to-left.
See also arithmetic operators, associativity, binary operator, Boolean operator, operand, operator, precedence.