Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Click here to view the latest version of this page.
Front Page / Metafunctions / Arithmetic Operations / negate

negate

Synopsis

template<
      typename T
    >
struct negate
{
    typedef unspecified type;
};

Description

Returns the negative (additive inverse) of its argument.

Header

#include <boost/mpl/negate.hpp>
#include <boost/mpl/arithmetic.hpp>

Model of

Numeric Metafunction

Parameters

Parameter Requirement Description
T Integral Constant Operation's argument.

[Note: The requirements listed in this specification are the ones imposed by the default implementation. See Numeric Metafunction concept for the details on how to provide an implementation for a user-defined numeric type that does not satisfy the Integral Constant requirements. — end note]

Expression semantics

For any Integral Constant c:

typedef negate<c>::type r;
Return type:

Integral Constant.

Semantics:

Equivalent to

typedef integral_c< c::value_type, ( -c::value ) > r;
typedef negate<c> r;
Return type:

Integral Constant.

Semantics:

Equivalent to

struct r : negate<c>::type {};

Complexity

Amortized constant time.

Example

typedef negate< int_<-10> >::type r;
BOOST_MPL_ASSERT_RELATION( r::value, ==, 10 );
BOOST_MPL_ASSERT(( is_same< r::value_type, int > ));

See also

Arithmetic Operations, Numeric Metafunction, numeric_cast, plus, minus, times