.. Data Types/Concepts//Integral Constant

Integral Constant

Description

An |Integral Constant| is a holder class for a compile-time value of an integral type. Every |Integral Constant| is also a nullary |Metafunction|, returning itself. An integral constant object is implicitly convertible to the corresponding run-time value of the wrapped integral type.

Expression requirements

|In the following table...| n is a model of |Integral Constant|.

+-----------------------------------+---------------------------------------+---------------------------+ | Expression | Type | Complexity | +===================================+=======================================+===========================+ | n::tag | integral_c_tag | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+ | n::value_type | An integral type | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+ | n::value | An integral constant expression | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+ | n::type | |Integral Constant| | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+ | next<n>::type | |Integral Constant| | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+ | prior<n>::type | |Integral Constant| | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+ | n::value_type const c = n() | | Constant time. | +-----------------------------------+---------------------------------------+---------------------------+

Expression semantics

+---------------------------------------+-----------------------------------------------------------+ | Expression | Semantics | +=======================================+===========================================================+ | n::tag | n\ 's tag type; n::tag::value is n\ 's | | | conversion rank. | +---------------------------------------+-----------------------------------------------------------+ | n::value_type | A cv-unqualified type of n::value. | +---------------------------------------+-----------------------------------------------------------+ | n::value | The value of the wrapped integral constant. | +---------------------------------------+-----------------------------------------------------------+ | n::type | is_same<n::type,n>::value == true. | +---------------------------------------+-----------------------------------------------------------+ | next<n>::type | An |Integral Constant| c of type n::value_type | | | such that c::value == n::value + 1. | +---------------------------------------+-----------------------------------------------------------+ | prior<n>::type | An |Integral Constant| c of type n::value_type | | | such that c::value == n::value - 1. | +---------------------------------------+-----------------------------------------------------------+ | n::value_type const c = n() | c == n::value. | +---------------------------------------+-----------------------------------------------------------+

Models

• |bool_|
• |int_|
• |long_|
• |char_|
• |integral_c|

See also

|Data Types|, |Integral Sequence Wrapper|, |integral_c|

.. copyright:: Copyright 2001-2009 Aleksey Gurtovoy and David Abrahams Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)