101 lines
2.7 KiB
Plaintext
101 lines
2.7 KiB
Plaintext
[/
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Boost.Optional
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Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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]
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[section bounds<> traits class]
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[section Introduction]
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To determine the ranges of numeric types with `std::numeric_limits` \[18.2.1\],
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different syntax have to be used depending on numeric type. Specifically,
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`numeric_limits<T>::min()` for integral types returns the minimum finite value,
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whereas for floating point types it returns the minimum positive normalized
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value. The difference in semantics makes client code unnecessarily complex
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and error prone.
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`boost::numeric::bounds<>` provides a consistent interface for retrieving the
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maximum finite value, the minimum finite value and the minimum positive normalized
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value (0 for integral types) for numeric types. The selection of implementation
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is performed at compile time, so there is no runtime overhead.
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[endsect]
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[section traits class bounds<N>]
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template<class N>
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struct bounds
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{
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static N lowest () { return implementation_defined; }
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static N highest () { return implementation_defined; }
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static N smallest() { return implementation_defined; }
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};
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[heading Members]
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[: `lowest()` ]
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Returns the minimum finite value, equivalent to `numeric_limits<T>::min()` when `T`
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is an integral type, and to `-numeric_limits<T>::max()` when `T` is a floating point type.
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[: `highest()` ]
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Returns the maximum finite value, equivalent to `numeric_limits<T>::max()`.
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[: `smallest()` ]
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Returns the smallest positive normalized value for floating point types with
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denormalization, or returns 0 for integral types.
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[endsect]
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[section Examples]
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The following example demonstrates the use of `numeric::bounds<>` and the
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equivalent code using `numeric_limits`:
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#include <iostream>
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#include <boost/numeric/conversion/bounds.hpp>
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#include <boost/limits.hpp>
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int main() {
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std::cout << "numeric::bounds versus numeric_limits example.\n";
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std::cout << "The maximum value for float:\n";
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std::cout << boost::numeric::bounds<float>::highest() << "\n";
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std::cout << std::numeric_limits<float>::max() << "\n";
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std::cout << "The minimum value for float:\n";
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std::cout << boost::numeric::bounds<float>::lowest() << "\n";
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std::cout << -std::numeric_limits<float>::max() << "\n";
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std::cout << "The smallest positive value for float:\n";
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std::cout << boost::numeric::bounds<float>::smallest() << "\n";
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std::cout << std::numeric_limits<float>::min() << "\n";
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return 0;
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}
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[endsect]
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[endsect]
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