operator unary- abstract method
The negation of this value.
The negation of a number is a number of the same kind
(int or double) representing the negation of the
numbers numerical value (the result of subtracting the
number from zero), if that value exists.
Negating a double gives a number with the same magnitude
as the original value (number.abs() == (-number).abs()),
and the opposite sign (-(number.sign) == (-number).sign).
Negating an integer, -number, is equivalent to subtracting
it from zero, 0 - number.
(Both properties generally also hold for the other type, but with a few edge case exceptions).
Implementation
num operator -();