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

This is the documentation for an old version of Boost. Click here to view this page for the latest version.
Front Page / Metafunctions / Arithmetic Operations / minus



      typename T1
    , typename T2
    , typename T3 = unspecified
    , typename Tn = unspecified
struct minus
    typedef unspecified type;


Returns the difference of its arguments.


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

Model of

Numeric Metafunction


Parameter Requirement Description
T1, T2,... Tn Integral Constant Operation's arguments.

[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 Constants c1,c2,... cn:

typedef minus<c1,>::type r;
Return type:

Integral Constant.


Equivalent to

typedef integral_c<
      typeof(c1::value - c2::value)
    , ( c1::value - c2::value )
    > c;

typedef minus<c,c3,>::type r;
typedef minus<c1,> r;
Return type:

Integral Constant.


Equivalent to

struct r : minus<c1,>::type {};


Amortized constant time.


typedef minus< int_<-10>, int_<3>, long_<1> >::type r;
BOOST_MPL_ASSERT_RELATION( r::value, ==, -14 );
BOOST_MPL_ASSERT(( is_same< r::value_type, long > ));

See also

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