Unary Plus and Negation Operators: + and -

 

The latest version of this topic can be found at Unary Plus and Negation Operators: + and -.

Syntax

  
+ cast-expression  

  
- cast-expression  

+ operator

The result of the unary plus operator (+) is the value of its operand. The operand to the unary plus operator must be of an arithmetic type.

Integral promotion is performed on integral operands. The resultant type is the type to which the operand is promoted. Thus, the expression +ch, where ch is of type char, results in type int; the value is unmodified. See Integral Promotions for more information about how the promotion is done.

- operator

The unary negation operator (–) produces the negative of its operand. The operand to the unary negation operator must be an arithmetic type.

Integral promotion is performed on integral operands, and the resultant type is the type to which the operand is promoted. See Integral Promotions for more information about how the promotion is performed.

Microsoft specific

Unary negation of unsigned quantities is performed by subtracting the value of the operand from 2^n, where n is the number of bits in an object of the given unsigned type. (Microsoft C++ runs on processors that utilize two's-complement arithmetic. On other processors, the algorithm for negation can differ.)

See Also

Expressions with Unary Operators
C++ Operators
C++ Built-in Operators, Precedence and Associativity