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Expressions with Unary Operators

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

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:

unary-operator cast-expression 
sizeof .unary-expression 
sizeof ( type-name ) 

The unary-operator may be one of

* & + – ! ~

Any postfix expression is considered a unary expression, and since any primary expression is considered a postfix expression, all primary expressions are considered unary expressions as well. For more information, see Postfix Expressions and Primary Expressions.

The allocation-expression refers to the new operator. The deallocation-expression refers to the delete operator. See the links above.

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