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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="math_toolkit.fp_facets.reference"></a><a class="link" href="reference.html" title="Reference">Reference</a>
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</h3></div></div></div>
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<h6>
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<a name="math_toolkit.fp_facets.reference.h0"></a>
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<span class="phrase"><a name="math_toolkit.fp_facets.reference.the_facet_nonfinite_num_put"></a></span><a class="link" href="reference.html#math_toolkit.fp_facets.reference.the_facet_nonfinite_num_put">The
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Facet <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code></a>
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</h6>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span>
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<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>
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<span class="special">></span>
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<span class="keyword">class</span> <span class="identifier">nonfinite_num_put</span><span class="special">;</span>
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</pre>
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<p>
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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.
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The first template argument is the character type of the formatted strings,
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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
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type of iterator used to write the strings. It is required to be an output
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iterator. Usually the default <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostreambuf_iterator</span></code>
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is used. The public interface of the class consists of a single constructor
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only:
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</p>
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<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>
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</pre>
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<p>
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The flags argument (effectively optional because a default of <code class="computeroutput"> <span class="identifier">no_flags</span></code> is provided) is discussed below.
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The class template <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code>
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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>.
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</p>
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<p>
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Unlike the C++ Standard facet <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_put</span></code>,
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the facet <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code>
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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.
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It uses the following string representations:
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</p>
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<div class="informaltable"><table class="table">
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<colgroup>
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<thead><tr>
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Number
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String
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</tr></thead>
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<tbody>
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<p>
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Positive infinity
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</p>
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</td>
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<td>
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<p>
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inf
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</p>
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</tr>
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<tr>
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<td>
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<p>
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Positive NaN
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</p>
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</td>
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<td>
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<p>
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nan
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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Negative infinity
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</p>
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</td>
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<td>
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<p>
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-inf
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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Negative NaN
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</p>
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</td>
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<td>
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<p>
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-nan
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<p>
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The numbers can be of type <code class="computeroutput"><span class="keyword">float</span></code>,
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<code class="computeroutput"><span class="keyword">double</span></code> and <code class="computeroutput"><span class="keyword">long</span>
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<span class="keyword">double</span></code>. The strings can be in all
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lower case or all upper case. An optional + sign can be used with positive
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numbers. This can be controlled with the <code class="computeroutput"><span class="identifier">uppercase</span></code>,
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<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>
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manipulators. Formatting of integers, boolean values and finite floating-point
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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>.
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</p>
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<h6>
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<a name="math_toolkit.fp_facets.reference.h1"></a>
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<span class="phrase"><a name="math_toolkit.fp_facets.reference.facet_nonfinite_num_get"></a></span><a class="link" href="reference.html#math_toolkit.fp_facets.reference.facet_nonfinite_num_get">Facet
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<code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code></a>
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</h6>
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<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>
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</pre>
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<p>
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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
|
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that represent numbers. The first template argument is the character type
|
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of the strings, usually <code class="computeroutput"><span class="keyword">char</span></code>
|
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or <code class="computeroutput"><span class="keyword">wchar_t</span></code>. The second template
|
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argument is the type of iterator used to read the strings. It is required
|
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to be an input iterator. Usually the default is used. The public interface
|
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of the class consists of a single constructor only:
|
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</p>
|
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<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>
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</pre>
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<p>
|
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The flags argument is discussed below. The <code class="computeroutput"><span class="keyword">class</span>
|
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<span class="keyword">template</span> <span class="identifier">nonfinite_num_get</span></code>
|
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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>
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<span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span></code>.
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</p>
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<p>
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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>
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parses strings that represent <code class="computeroutput"><span class="identifier">infinity</span></code>
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and <code class="computeroutput"><span class="identifier">NaN</span></code> in a consistent and
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portable manner. It recognizes precisely the string representations specified
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by the C99 standard:
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</p>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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Number
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</p>
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</th>
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<th>
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<p>
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String
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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Positive infinity
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</p>
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</td>
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<td>
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<p>
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inf, infinity
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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Positive NaN
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</p>
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</td>
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<td>
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<p>
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nan, nan(...)
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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Negative infinity
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</p>
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</td>
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<td>
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<p>
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-inf, -infinity
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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Negative NaN
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</p>
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</td>
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<td>
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<p>
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-nan, -nan(...)
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<p>
|
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The numbers can be of type <code class="computeroutput"><span class="keyword">float</span></code>,
|
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<code class="computeroutput"><span class="keyword">double</span></code> and <code class="computeroutput"><span class="keyword">long</span>
|
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<span class="keyword">double</span></code>. The facet is case-insensitive.
|
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An optional + sign can be used with positive numbers. The dots in nan(...)
|
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stand for an arbitrary string usually containing the <span class="emphasis"><em>NaN payload</em></span>.
|
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Parsing of strings that represent integers, boolean values and finite floating-point
|
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numbers is delegated to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_get</span></code>.
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</p>
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<p>
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When the facet parses a string that represents <code class="computeroutput"><span class="identifier">infinity</span></code>
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on a platform that lacks infinity, then the fail bit of the stream is set.
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</p>
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<p>
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When the facet parses a string that represents <code class="computeroutput"><span class="identifier">NaN</span></code>
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on a platform that lacks NaN, then the fail bit of the stream is set.
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</p>
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<h5>
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<a name="math_toolkit.fp_facets.reference.h2"></a>
|
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<span class="phrase"><a name="math_toolkit.fp_facets.reference.flags"></a></span><a class="link" href="reference.html#math_toolkit.fp_facets.reference.flags">Flags</a>
|
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</h5>
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<p>
|
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The constructors for <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code>
|
||
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and <code class="computeroutput"><span class="identifier">nonfinite_num_get</span></code> take
|
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an optional bit flags argument. There are four different bit flags:
|
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</p>
|
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
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<li class="listitem">
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legacy
|
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</li>
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<li class="listitem">
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signed_zero
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</li>
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<li class="listitem">
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trap_infinity
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</li>
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<li class="listitem">
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trap_nan
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</li>
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</ul></div>
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<p>
|
||
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The flags can be combined with the OR <code class="computeroutput"><span class="keyword">operator</span><span class="special">|</span></code>.
|
||
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</p>
|
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<p>
|
||
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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>
|
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<span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span></code>.
|
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</p>
|
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<h6>
|
||
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<a name="math_toolkit.fp_facets.reference.h3"></a>
|
||
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<span class="phrase"><a name="math_toolkit.fp_facets.reference.legacy"></a></span><a class="link" href="reference.html#math_toolkit.fp_facets.reference.legacy">legacy</a>
|
||
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</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 class="itemizedlist" style="list-style-type: disc; ">
|
||
|
|
<li class="listitem">
|
||
|
|
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 class="listitem">
|
||
|
|
The facet is case-insensitive.
|
||
|
|
</li>
|
||
|
|
<li class="listitem">
|
||
|
|
An optional <code class="computeroutput"><span class="special">+</span></code> sign can be
|
||
|
|
used with the positive values.
|
||
|
|
</li>
|
||
|
|
<li class="listitem">
|
||
|
|
The dots in <code class="computeroutput"><span class="identifier">nan</span><span class="special">(...)</span></code>
|
||
|
|
stand for an arbitrary string.
|
||
|
|
</li>
|
||
|
|
<li class="listitem">
|
||
|
|
<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>
|
||
|
|
<h6>
|
||
|
|
<a name="math_toolkit.fp_facets.reference.h4"></a>
|
||
|
|
<span class="phrase"><a name="math_toolkit.fp_facets.reference.signed_zero"></a></span><a class="link" href="reference.html#math_toolkit.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 always 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>
|
||
|
|
<div class="note"><table border="0" summary="Note">
|
||
|
|
<tr>
|
||
|
|
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
|
||
|
|
<th align="left">Note</th>
|
||
|
|
</tr>
|
||
|
|
<tr><td align="left" valign="top"><p>
|
||
|
|
If the <code class="computeroutput"><span class="identifier">signed_zero</span></code> flag
|
||
|
|
is not set (the default), then a negative zero value will be displayed
|
||
|
|
on output in whatever way the platform normally handles it. For most platforms,
|
||
|
|
this it will format positive zero as "0" or "+0" and
|
||
|
|
negative zero as "-0". But setting the <code class="computeroutput"><span class="identifier">signed_zero</span></code>
|
||
|
|
flag may be more portable.
|
||
|
|
</p></td></tr>
|
||
|
|
</table></div>
|
||
|
|
<div class="tip"><table border="0" summary="Tip">
|
||
|
|
<tr>
|
||
|
|
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../../../doc/src/images/tip.png"></td>
|
||
|
|
<th align="left">Tip</th>
|
||
|
|
</tr>
|
||
|
|
<tr><td align="left" valign="top"><p>
|
||
|
|
A negative zero value can be portably produced using the changesign function
|
||
|
|
<code class="computeroutput"><span class="special">(</span><span class="identifier">changesign</span><span class="special">)(</span><span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">ValType</span><span class="special">>(</span><span class="number">0</span><span class="special">))</span></code>
|
||
|
|
where <code class="computeroutput"><span class="identifier">ValType</span></code> is <code class="computeroutput"><span class="keyword">float</span></code>, <code class="computeroutput"><span class="keyword">double</span></code>
|
||
|
|
or <code class="computeroutput"><span class="keyword">long</span> <span class="keyword">double</span></code>,
|
||
|
|
or a User-Defined floating-point type (UDT) provided that this UDT has
|
||
|
|
a sign and that the changesign function is implemented.
|
||
|
|
</p></td></tr>
|
||
|
|
</table></div>
|
||
|
|
<h6>
|
||
|
|
<a name="math_toolkit.fp_facets.reference.h5"></a>
|
||
|
|
<span class="phrase"><a name="math_toolkit.fp_facets.reference.trap_infinity"></a></span><a class="link" href="reference.html#math_toolkit.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>
|
||
|
|
<h6>
|
||
|
|
<a name="math_toolkit.fp_facets.reference.h6"></a>
|
||
|
|
<span class="phrase"><a name="math_toolkit.fp_facets.reference.trap_nan"></a></span><a class="link" href="reference.html#math_toolkit.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 © 2006-2010, 2012-2014 Nikhar Agrawal,
|
||
|
|
Anton Bikineev, Paul A. Bristow, Marco Guazzone, Christopher Kormanyos, Hubert
|
||
|
|
Holin, Bruno Lalande, John Maddock, Jeremy Murphy, Johan Råde, Gautam Sewani,
|
||
|
|
Benjamin Sobotta, Thijs van den Berg, Daryle Walker and Xiaogang Zhang<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>
|
||
|
|
<div class="spirit-nav">
|
||
|
|
<a accesskey="p" href="facets_intro.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../fp_facets.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="examples.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|