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| <div class="section" lang="en"> |
| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="math_toolkit.utils.fp_facets.reference"></a><a class="link" href="reference.html" title="Reference">Reference</a> |
| </h4></div></div></div> |
| <a name="math_toolkit.utils.fp_facets.reference.the_facet__code__phrase_role__identifier__nonfinite_num_put__phrase___code_"></a><h6> |
| <a name="id1330057"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.the_facet__code__phrase_role__identifier__nonfinite_num_put__phrase___code_">The |
| Facet <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code></a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">class</span> <span class="identifier">CharType</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">OutputIterator</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">ostreambuf_iterator</span><span class="special"><</span><span class="identifier">CharType</span><span class="special">></span> |
| <span class="special">></span> |
| <span class="keyword">class</span> <span class="identifier">nonfinite_num_put</span><span class="special">;</span> |
| </pre> |
| <p> |
| The <code class="computeroutput"><span class="keyword">class</span> <span class="identifier">nonfinite_num_put</span><span class="special"><</span><span class="identifier">CharType</span><span class="special">,</span> <span class="identifier">OutputIterator</span><span class="special">></span></code> is derived from <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_put</span><span class="special"><</span><span class="identifier">CharType</span><span class="special">,</span> <span class="identifier">OutputIterator</span><span class="special">></span></code>. Thus it is a facet that formats numbers. |
| The first template argument is the character type of the formatted strings, |
| usually <code class="computeroutput"><span class="keyword">char</span></code> or <code class="computeroutput"><span class="keyword">wchar_t</span></code>. The second template argument is |
| the type of iterator used to write the strings. It is required to be an |
| output iterator. Usually the default <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostreambuf_iterator</span></code> |
| is used. The public interface of the class consists of a single constructor |
| only: |
| </p> |
| <pre class="programlisting"><span class="identifier">nonfinite_num_put</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">flags</span> <span class="special">=</span> <span class="number">0</span><span class="special">);</span> |
| </pre> |
| <p> |
| The flags argument (effectively optional because a default of <code class="computeroutput"> <span class="identifier">no_flags</span></code> is provided) is discussed below. |
| The class template <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code> |
| is defined in the header <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">nonfinite_num_facets</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| and lives in the namespace <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span></code>. |
| </p> |
| <p> |
| Unlike the C++ Standard facet <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_put</span></code>, |
| the facet <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code> |
| formats <code class="computeroutput"><span class="identifier">infinity</span></code> and <code class="computeroutput"><span class="identifier">NaN</span></code> in a consistent and portable manner. |
| It uses the following string representations: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Number |
| </p> |
| </th> |
| <th> |
| <p> |
| String |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| Positive infinity |
| </p> |
| </td> |
| <td> |
| <p> |
| inf |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Positive NaN |
| </p> |
| </td> |
| <td> |
| <p> |
| nan |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Negative infinity |
| </p> |
| </td> |
| <td> |
| <p> |
| -inf |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Negative NaN |
| </p> |
| </td> |
| <td> |
| <p> |
| -nan |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <p> |
| The numbers can be of type <code class="computeroutput"><span class="keyword">float</span></code>, |
| <code class="computeroutput"><span class="keyword">double</span></code> and <code class="computeroutput"><span class="keyword">long</span> |
| <span class="keyword">double</span></code>. The strings can be in all |
| lower case or all upper case. An optional + sign can be used with positive |
| numbers. This can be controlled with the <code class="computeroutput"><span class="identifier">uppercase</span></code>, |
| <code class="computeroutput"><span class="identifier">lowercase</span></code>, <code class="computeroutput"><span class="identifier">showpos</span></code> and <code class="computeroutput"><span class="identifier">noshowpos</span></code> |
| manipulators. Formatting of integers, boolean values and finite floating-point |
| numbers is simply delegated to the normal <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_put</span></code>. |
| </p> |
| <a name="math_toolkit.utils.fp_facets.reference.facet__code__phrase_role__identifier__nonfinite_num_get__phrase___code_"></a><h6> |
| <a name="id1330570"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.facet__code__phrase_role__identifier__nonfinite_num_get__phrase___code_">Facet |
| <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code></a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">CharType</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">InputIterator</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">istreambuf_iterator</span><span class="special"><</span><span class="identifier">CharType</span><span class="special">></span> <span class="special">></span> <span class="keyword">class</span> <span class="identifier">nonfinite_num_get</span><span class="special">;</span> |
| </pre> |
| <p> |
| The class <code class="computeroutput"><span class="identifier">nonfinite_num_get</span><span class="special"><</span><span class="identifier">CharType</span><span class="special">,</span> <span class="identifier">InputIterator</span><span class="special">></span></code> is derived from <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_get</span><span class="special"><</span><span class="identifier">CharType</span><span class="special">,</span> <span class="identifier">IntputIterator</span><span class="special">></span></code>. Thus it is a facet that parses strings |
| that represent numbers. The first template argument is the character type |
| of the strings, usually <code class="computeroutput"><span class="keyword">char</span></code> |
| or <code class="computeroutput"><span class="keyword">wchar_t</span></code>. The second template |
| argument is the type of iterator used to read the strings. It is required |
| to be an input iterator. Usually the default is used. The public interface |
| of the class consists of a single constructor only: |
| </p> |
| <pre class="programlisting"><span class="identifier">nonfinite_num_get</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">flags</span> <span class="special">=</span> <span class="number">0</span><span class="special">);</span> |
| </pre> |
| <p> |
| The flags argument is discussed below. The <code class="computeroutput"><span class="keyword">class</span> |
| <span class="keyword">template</span> <span class="identifier">nonfinite_num_get</span></code> |
| is defined in the header <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">nonfinite_num_facets</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| and lives in the <code class="computeroutput"><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span></code>. |
| </p> |
| <p> |
| Unlike the facet <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_get</span></code>, the facet <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code> |
| parses strings that represent <code class="computeroutput"><span class="identifier">infinity</span></code> |
| and <code class="computeroutput"><span class="identifier">NaN</span></code> in a consistent |
| and portable manner. It recognizes precisely the string representations |
| specified by the C99 standard: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Number |
| </p> |
| </th> |
| <th> |
| <p> |
| String |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| Positive infinity |
| </p> |
| </td> |
| <td> |
| <p> |
| inf, infinity |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Positive NaN |
| </p> |
| </td> |
| <td> |
| <p> |
| nan, nan(...) |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Negative infinity |
| </p> |
| </td> |
| <td> |
| <p> |
| -inf, -infinity |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Negative NaN |
| </p> |
| </td> |
| <td> |
| <p> |
| -nan, -nan(...) |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <p> |
| The numbers can be of type <code class="computeroutput"><span class="keyword">float</span></code>, |
| <code class="computeroutput"><span class="keyword">double</span></code> and <code class="computeroutput"><span class="keyword">long</span> |
| <span class="keyword">double</span></code>. The facet is case-insensitive. |
| An optional + sign can be used with positive numbers. The dots in nan(...) |
| stand for an arbitrary string usually containing the <span class="emphasis"><em>NaN payload</em></span>. |
| Parsing of strings that represent integers, boolean values and finite floating-point |
| numbers is delegated to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_get</span></code>. |
| </p> |
| <p> |
| When the facet parses a string that represents <code class="computeroutput"><span class="identifier">infinity</span></code> |
| on a platform that lacks infinity, then the fail bit of the stream is set. |
| </p> |
| <p> |
| When the facet parses a string that represents <code class="computeroutput"><span class="identifier">NaN</span></code> |
| on a platform that lacks NaN, then the fail bit of the stream is set. |
| </p> |
| <a name="math_toolkit.utils.fp_facets.reference.flags"></a><h5> |
| <a name="id1331066"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.flags">Flags</a> |
| </h5> |
| <p> |
| The constructors for <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code> |
| and <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code> take |
| an optional bit flags argument. There are four different bit flags: |
| </p> |
| <div class="itemizedlist"><ul type="disc"> |
| <li> |
| legacy |
| </li> |
| <li> |
| signed_zero |
| </li> |
| <li> |
| trap_infinity |
| </li> |
| <li> |
| trap_nan |
| </li> |
| </ul></div> |
| <p> |
| The flags can be combined with the OR <code class="computeroutput"><span class="keyword">operator</span><span class="special">|</span></code>. |
| </p> |
| <p> |
| The flags are defined in the header <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">nonfinite_num_facets</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| and live in the <code class="computeroutput"><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span></code>. |
| </p> |
| <a name="math_toolkit.utils.fp_facets.reference.legacy"></a><h6> |
| <a name="id1331196"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.legacy">legacy</a> |
| </h6> |
| <p> |
| The legacy flag has no effect with the output facet <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code>. |
| </p> |
| <p> |
| If the legacy flag is used with the <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code> |
| input facet, then the facet will recognize all the following string representations |
| of <code class="computeroutput"><span class="identifier">infinity</span></code> and <code class="computeroutput"><span class="identifier">NaN</span></code>: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Number |
| </p> |
| </th> |
| <th> |
| <p> |
| String |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| Positive infinity |
| </p> |
| </td> |
| <td> |
| <p> |
| inf, infinity, one#inf |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Positive NaN |
| </p> |
| </td> |
| <td> |
| <p> |
| nan, nan(...), nanq, nans, qnan, snan, one#ind, one#qnan, one#snan |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Negative infinity |
| </p> |
| </td> |
| <td> |
| <p> |
| -inf, -infinity, -one#inf |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Negative NaN |
| </p> |
| </td> |
| <td> |
| <p> |
| -nan, -nan(...), -nanq, -nans, -qnan, -snan, -one#ind, - one#qnan, |
| -one#snan |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <div class="itemizedlist"><ul type="disc"> |
| <li> |
| The numbers can be of type <code class="computeroutput"><span class="keyword">float</span></code>, |
| <code class="computeroutput"><span class="keyword">double</span></code> and <code class="computeroutput"><span class="keyword">long</span> <span class="keyword">double</span></code>. |
| </li> |
| <li> |
| The facet is case-insensitive. |
| </li> |
| <li> |
| An optional <code class="computeroutput"><span class="special">+</span></code> sign can |
| be used with the positive values. |
| </li> |
| <li> |
| The dots in <code class="computeroutput"><span class="identifier">nan</span><span class="special">(...)</span></code> |
| stand for an arbitrary string. |
| </li> |
| <li> |
| <code class="computeroutput"><span class="identifier">one</span></code> stands for any |
| string that <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_get</span></code> parses as the number <code class="computeroutput"><span class="number">1</span></code>, typically "1.#INF", "1.QNAN" |
| but also "000001.#INF"... |
| </li> |
| </ul></div> |
| <p> |
| The list includes a number of non-standard string representations of infinity |
| and NaN that are used by various existing implementations of the C++ standard |
| library, and also string representations used by other programming languages. |
| </p> |
| <a name="math_toolkit.utils.fp_facets.reference.signed_zero"></a><h6> |
| <a name="id1331470"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.signed_zero">signed_zero</a> |
| </h6> |
| <p> |
| If the <code class="computeroutput"><span class="identifier">signed_zero</span></code> flag |
| is used with <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code>, |
| then the facet will distinguish between positive and negative zero. It |
| will format positive zero as "0" or "+0" and negative |
| zero as "-0". The string representation of positive zero can |
| be controlled with the <code class="computeroutput"><span class="identifier">showpos</span></code> |
| and <code class="computeroutput"><span class="identifier">noshowpos</span></code> manipulators. |
| </p> |
| <p> |
| The <code class="computeroutput"><span class="identifier">signed_zero</span> <span class="identifier">flag</span></code> |
| has no effect with the input facet <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code>. |
| The input facet <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code> |
| always parses "0" and "+0" as positive zero and "-0" |
| as negative zero, as do most implementations of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_get</span></code>. |
| </p> |
| <a name="math_toolkit.utils.fp_facets.reference.trap_infinity"></a><h6> |
| <a name="id1331562"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.trap_infinity">trap_infinity</a> |
| </h6> |
| <p> |
| If the <code class="computeroutput"><span class="identifier">trap_infinity</span></code> flag |
| is used with <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code>, |
| then the facet will throw an exception of type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios_base</span><span class="special">::</span><span class="identifier">failure</span></code> |
| when an attempt is made to format positive or negative infinity. If the |
| facet is called from a stream insertion operator, then the stream will |
| catch that exception and set either its <code class="computeroutput"><span class="identifier">fail</span> |
| <span class="identifier">bit</span></code> or its <code class="computeroutput"><span class="identifier">bad</span> |
| <span class="identifier">bit</span></code>. Which bit is set is platform |
| dependent. |
| </p> |
| <p> |
| If the <code class="computeroutput"><span class="identifier">trap_infinity</span></code> flag |
| is used with <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code>, |
| then the facet will set the <code class="computeroutput"><span class="identifier">fail</span> |
| <span class="identifier">bit</span></code> of the stream when an attempt |
| is made to parse a string that represents positive or negative infinity. |
| </p> |
| <p> |
| (See Design Rationale below for a discussion of this inconsistency.) |
| </p> |
| <a name="math_toolkit.utils.fp_facets.reference.trap_nan"></a><h6> |
| <a name="id1331675"></a> |
| <a class="link" href="reference.html#math_toolkit.utils.fp_facets.reference.trap_nan">trap_nan</a> |
| </h6> |
| <p> |
| Same as <code class="computeroutput"><span class="identifier">trap_infinity</span></code>, |
| but positive and negative NaN are trapped instead. |
| </p> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2006 , 2007, 2008, 2009, 2010 John Maddock, Paul A. Bristow, |
| Hubert Holin, Xiaogang Zhang, Bruno Lalande, Johan Råde, Gautam Sewani and |
| Thijs van den Berg<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
| </p> |
| </div></td> |
| </tr></table> |
| <hr> |
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