Unary operators act on only one operand in an expression. The unary operators are as follows:

• Indirection operator (*)

• Address-of operator (&)

• Unary plus operator (+)

• Unary negation operator (–)

• Logical negation operator (!)

• One's complement operator (~)

• Prefix increment operator (++)

• Prefix decrement operator (––)

• Cast operator ()

• sizeof operator

• __uuidof operator

• __alignof operator

• new operator

• delete operator

These operators have right-to-left associativity. Unary expressions generally involve syntax that precedes a postfix or primary expression.

The following are the possible forms of unary expressions.

• postfix-expression

• ++ unary-expression

• –– unary-expression

• unary-operator cast-expression

• sizeof unary-expression

• sizeof( type-name )

• decltype( expression )

• allocation-expression

• deallocation-expression

Any postfix-expression is considered a unary-expression, and because any primary expression is considered a postfix-expression, any primary expressions is considered a unary-expression also. For more information, see Postfix Expressions and Primary Expressions.

A unary-operator consists of one or more of the following symbols: * &``+``–``!``~

The cast-expression is a unary expression with an optional cast to change the type. For more information see Cast Operator: ().

An expression can be any expression. For more information, see Expressions.

The allocation-expression refers to the new operator. The deallocation-expression refers to the delete operator. For more information, see the links earlier in this topic.

Types of Expressions