Synopsis

template<
      typename T1
    , typename T2
    >
struct equal_to
{
    typedef unspecified type;
};

Description

Returns a true-valued Integral Constant if T1 and T2 are equal.

Header

#include <boost/mpl/equal_to.hpp>
#include <boost/mpl/comparison.hpp>

Model of

Numeric Metafunction

Parameters

[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 and c2:

typedef equal_to<c1,c2>::type r;

typedef bool_< (c1::value == c2::value) > r;

typedef equal_to<c1,c2> r;

struct r : equal_to<c1,c2>::type {};

Complexity

Amortized constant time.

Example

BOOST_MPL_ASSERT_NOT(( equal_to< int_<0>, int_<10> > ));
BOOST_MPL_ASSERT_NOT(( equal_to< long_<10>, int_<0> > ));
BOOST_MPL_ASSERT(( equal_to< long_<10>, int_<10> > ));

See also

Comparisons, Numeric Metafunction, numeric_cast, not_equal_to, less