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<H1 ALIGN="center">Boost Numeric Conversion Library</H1> </TH>
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<td width="50%" valign="top"><font size="4">This Document</font><br><br>
<a href="#Overview">Overview</a><br>
<a href="#Ack">History and Acknowledgments</a><br>
<a href="#Ref">Bibliography</a><br>
</td>
<td width="50%"><font size="4">Other Documents</font><br><br>
<A HREF="definitions.html">Definitions</A><br>
<A HREF="converter.html"><code>converter<></code> function object</A><br>
<A HREF="requirements.html">Type Requirements and User-defined-types support</A><br>
<A HREF="bounds.html"><code>bounds<></code> traits class</A><br>
<A HREF="conversion_traits.html"><code>conversion_traits<></code> traits class</A><br>
<A HREF="converter_policies.html">Numeric Converter Policy Classes</A><br>
<A HREF="numeric_cast.html">Improved numeric_cast<></A><br>
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<hr>
<H2><A NAME="Overview"></A>Overview</H2>
<P>The Boost Numeric Conversion library is a collection of tools to describe and perform
conversions between values of different <a href="definitions.html#numtypes">numeric types</a>.</p>
<p>The library includes a special alternative for a subset of <code>std::numeric_limits<></code>,
the <A HREF="bounds.html"><code>bounds<></code></A> traits class, which provides
a consistent way to obtain the <a href="definitions.html#range">boundary</a> values for the
<a href="definitions.html#range">range</a> of a numeric type.</p>
<p>It also includes a set of <A HREF="conversion_traits.html">trait classes</A> which
describes the compile-time properties of a conversion from a source to a target
numeric type. Both <a href="definitions.html#stdtypes">arithmetic</a> and <a href="definitions.html#numtypes">user-defined
numeric types</a> can be used.</p>
<p>A policy-based <A HREF="converter.html">converter</A> object which uses <code>conversion_traits</code>
to select an optimized implementation is supplied.
Such implementation uses an optimal range checking code suitable for the source/target combination.<br>
The converter's out-of-range behavior can be customized via an <A HREF="converter_policies.html#oh">OverflowHandler</A>
policy.<br>
For floating-point to integral conversions, the rounding mode can be selected via
the <A HREF="converter_policies.html#f2i">Float2IntRounder</A> policy.<br>
A custom low-level conversion routine (for UDTs for instance) can be passed
via a <A HREF="converter_policies.html#rawc">RawConverter</A> policy.<br>
The optimized automatic range-checking logic can be overridden via a <A HREF="converter_policies.html#rc">UserRangeChecker</A>
policy.</p>
<hr>
<H2><A NAME="Ack"></A>History and Acknowledgments</H2>
<p>Pre-formal review:</p>
<blockquote>
<p>Kevlin Henney, with help from David Abrahams and Beman Dawes, originally contributed
the previous version of numeric_cast<> which already presented the idea of a runtime range check.<br>
Later, Eric Ford, Kevin Lynch and the author spotted some genericity problems
with that numeric_cast<> which prevented it from being used in a generic
layer of math functions.<br>
An improved numeric_cast<> which properly handled all combinations of arithmetic types was presented.<br>
David Abrahams and Beman Dawes acknowledged the need of an improved version
of numeric_cast<> and supported the submission as originally laid out.
Daryl Walker and Darin Adler made some important comments and proposed fixes
to the original submission.</p>
<p>Special thanks go to Bjrn Karlsoon who helped the author considerably. Having
found the problems with numeric_cast<> himself, he revised very carefully
the original submission and spot a subtle bug in the range checking implementation.
He also wrote part of this documentation and proof-read and corrected other
parts. And most importantly: the features now presented here in this library
evolved from the original submission as a result of the useful private communications
between Bjrn and the author.</p>
</blockquote>
<p>Post-formal review:</p>
<p>Guillaume Melquiond spoted some documentation and code issues, particularly about rounding conversions.<br>
The following people contributed an important review of the design, documentation and code: Kevin Lynch, Thorsten Ottosen, Paul Bristow,
Daryle Walker, Jhon Torjo, Eric Ford, Gennadiy Rozental.
</p>
<hr>
<H2><A NAME="Ref"></A>Bibliography</H2>
<ul>
<li>Standard Documents:
<ol>
<li>ISO/IEC 14882:98 (C++98 Standard)</li>
<li>ISO/IEC 9899:1999 (C99 Standard)</li>
<li>ISO/IEC 10967-1 (Language Independent Arithmetic (LIA), Part I, 1994)</li>
<li>ISO/IEC 2382-1:1993 (Information Technology - Vocabulary - Part I: Fundamental Terms)</li>
<li>ANSI/IEEE 754-1985 [and IEC 60559:1989] (Binary floating-point)</li>
<li>ANSI/IEEE 854-1988 (Radix Independent floating-point)</li>
<li>ANSI X3/TR-1-82 (Dictionary for Information Processing Systems)</li>
<li><a href="http://anubis.dkuug.dk/JTC1/SC22/WG14/www/docs/n753.htm">ISO/IEC JTC1/SC22/WG14/N753</a> C9X Revision Proposal: LIA-1 Binding: Rationale</li>
</ol>
</li>
<li>Papers:
<ol>
<li>David Goldberg <A href="http://citeseer.ist.psu.edu/goldberg91what.html">
What Every Computer Scientist Should Know About Floating-Point Arithmetic</A></li>
<li><A href="http://www.cs.berkeley.edu/~wkahan/">Prof. William Kahan</A> papers on floating-point.</li>
</ol>
</li>
</ul>
<HR>
<P>Revised 23 June 2004</P>
<p> Copyright Fernando Luis Cacciola Carballal, 2004</p>
<p> Use, modification, and distribution are subject to the Boost Software
License, Version 1.0. (See accompanying file <a href="../../../../LICENSE_1_0.txt">
LICENSE_1_0.txt</a> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">
www.boost.org/LICENSE_1_0.txt</a>)</p>
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