A unary arithmetic operator combined with a single operand
forms a unary expression used to negate a variable, or determine
the ones complement or logical complement of the variable.
Description |
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The unary plus operator operates on a single arithmetic operand,
as is the case of the unary minus operator. The result of the unary
plus operator is defined to be the value of its operand. For example,
just as -2 is
an expression with the value negative 2, +2
is an expression with the value positive 2.
In spite of its definition, the unary plus operator is not
purely a no-op. According to the ANSI standard, an unary plus operation
is an expression that follows the integral promotion rule. For example,
if i is defined
as a short int, then sizeof (i )
is 2. However, sizeof (+i)
is 4 because the unary plus operator promotes i
to an int. The result of the unary -
operator is the negative value of its operand. The operand can be
any arithmetic type. The integral promotion is performed on the
operand before it is used. The result has the promoted type and
is not an lvalue.
The result of the unary ~
operator is a one's (bitwise) complement of its operand. The operand
can be of any integral type. The integral promotion is performed
on the operand before it is used. The result has the promoted type
and is not an lvalue.
The result of the unary !
operator is the logical complement of its operand. The operand can
be of any scalar type. The result has type int and is not an lvalue.
If the operand had a zero value, the result is 1. If the operand
had a nonzero value, the result is 0.
