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<a name="Rational-Conversions"></a>
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<p>
Next: <a href="Rational-Arithmetic.html#Rational-Arithmetic" accesskey="n" rel="next">Rational Arithmetic</a>, Previous: <a href="Initializing-Rationals.html#Initializing-Rationals" accesskey="p" rel="prev">Initializing Rationals</a>, Up: <a href="Rational-Number-Functions.html#Rational-Number-Functions" accesskey="u" rel="up">Rational Number Functions</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Conversion-Functions-1"></a>
<h3 class="section">6.2 Conversion Functions</h3>
<a name="index-Rational-conversion-functions"></a>
<a name="index-Conversion-functions-1"></a>
<dl>
<dt><a name="index-mpq_005fget_005fd"></a>Function: <em>double</em> <strong>mpq_get_d</strong> <em>(const mpq_t <var>op</var>)</em></dt>
<dd><p>Convert <var>op</var> to a <code>double</code>, truncating if necessary (i.e. rounding
towards zero).
</p>
<p>If the exponent from the conversion is too big or too small to fit a
<code>double</code> then the result is system dependent. For too big an infinity is
returned when available. For too small <em>0.0</em> is normally returned.
Hardware overflow, underflow and denorm traps may or may not occur.
</p></dd></dl>
<dl>
<dt><a name="index-mpq_005fset_005fd"></a>Function: <em>void</em> <strong>mpq_set_d</strong> <em>(mpq_t <var>rop</var>, double <var>op</var>)</em></dt>
<dt><a name="index-mpq_005fset_005ff"></a>Function: <em>void</em> <strong>mpq_set_f</strong> <em>(mpq_t <var>rop</var>, const mpf_t <var>op</var>)</em></dt>
<dd><p>Set <var>rop</var> to the value of <var>op</var>. There is no rounding, this conversion
is exact.
</p></dd></dl>
<dl>
<dt><a name="index-mpq_005fget_005fstr"></a>Function: <em>char *</em> <strong>mpq_get_str</strong> <em>(char *<var>str</var>, int <var>base</var>, const mpq_t <var>op</var>)</em></dt>
<dd><p>Convert <var>op</var> to a string of digits in base <var>base</var>. The base may vary
from 2 to 36. The string will be of the form ‘<samp>num/den</samp>’, or if the
denominator is 1 then just ‘<samp>num</samp>’.
</p>
<p>If <var>str</var> is <code>NULL</code>, the result string is allocated using the current
allocation function (see <a href="Custom-Allocation.html#Custom-Allocation">Custom Allocation</a>). The block will be
<code>strlen(str)+1</code> bytes, that being exactly enough for the string and
null-terminator.
</p>
<p>If <var>str</var> is not <code>NULL</code>, it should point to a block of storage large
enough for the result, that being
</p>
<div class="example">
<pre class="example">mpz_sizeinbase (mpq_numref(<var>op</var>), <var>base</var>)
+ mpz_sizeinbase (mpq_denref(<var>op</var>), <var>base</var>) + 3
</pre></div>
<p>The three extra bytes are for a possible minus sign, possible slash, and the
null-terminator.
</p>
<p>A pointer to the result string is returned, being either the allocated block,
or the given <var>str</var>.
</p></dd></dl>
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