boost_1_45_0/libs/numeric/conversion/doc/bounds.qbk

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    Boost.Optional

    Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal

    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)
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[section bounds<> traits class]

[section Introduction]

To determine the ranges of numeric types with `std::numeric_limits` \[18.2.1\],
different syntax have to be used depending on numeric type. Specifically,
`numeric_limits<T>::min()` for integral types returns the minimum finite value,
whereas for floating point types it returns the minimum positive normalized
value. The difference in semantics makes client code unnecessarily complex
and error prone.

`boost::numeric::bounds<>` provides a consistent interface for retrieving the
maximum finite value, the minimum finite value and the minimum positive normalized
value (0 for integral types) for numeric types. The selection of implementation
is performed at compile time, so there is no runtime overhead.

[endsect]

[section traits class bounds<N>]

    template<class N>
    struct bounds
    {
        static N lowest  () { return implementation_defined; }
        static N highest () { return implementation_defined; }
        static N smallest() { return implementation_defined; }
    };

[heading Members]


[: `lowest()` ]

Returns the minimum finite value, equivalent to `numeric_limits<T>::min()` when `T`
is an integral type, and to `-numeric_limits<T>::max()` when `T` is a floating point type.

[: `highest()` ]

Returns the maximum finite value, equivalent to `numeric_limits<T>::max()`.

[: `smallest()` ]

Returns the smallest positive normalized value for floating point types with
denormalization, or returns 0 for integral types.

[endsect]

[section Examples]

The following example demonstrates the use of `numeric::bounds<>` and the
equivalent code using `numeric_limits`:

    #include <iostream>

    #include <boost/numeric/conversion/bounds.hpp>
    #include <boost/limits.hpp>

    int main() {

        std::cout << "numeric::bounds versus numeric_limits example.\n";

        std::cout << "The maximum value for float:\n";
        std::cout << boost::numeric::bounds<float>::highest() << "\n";
        std::cout << std::numeric_limits<float>::max() << "\n";

        std::cout << "The minimum value for float:\n";
        std::cout << boost::numeric::bounds<float>::lowest() << "\n";
        std::cout << -std::numeric_limits<float>::max() << "\n";

        std::cout << "The smallest positive value for float:\n";
        std::cout << boost::numeric::bounds<float>::smallest() << "\n";
        std::cout << std::numeric_limits<float>::min() << "\n";

        return 0;
    }


[endsect]

[endsect]