Unary Operators

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Since a constant can be negative, we could have an expression like:


        2 * -3


Do not confuse the minus sign shown here for the minus sign used to do subtraction. This minus sign is called a unary operator because it operates only on the 3 and indicates that the 3 is negative.


Any factor (or sub-expression) can have the unary operators "-" and "+". Because the "+" operator really does not do anything, it can always be left out. It is sometimes used to emphasize that a number is positive.



When unary operators are used in expressions with other operators, the unary operations are done first unless parentheses are used to force a different order of evaluation.


Here are some expressions using unary operators:


        2 * -3   equals -6              +2 +2      equals 4

        6+ -4    equals 2               -$40/16    equals -4

        -4 - -6  equals 2               -^A + $41  equals 0

        -(4+6)   equals -10             2*--3      equals 6