Unary and Binary Operators

The two general classes of operators are:

unary	A unary operator operates on only one operand. A unary operator typically appears with its operand in this format:
	operator operand
binary	A binary operator operates on two operands. A binary operator appears with its operands in this format:
	operand1 operator operand2

Other operators with special formats accept more than two operands. If an operator is given a null operand, the result is always null. The only operator that does not follow this rule is concatenation (||).