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<title>Converting Floats (GNU MP 6.1.0)</title>
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<a name="Converting-Floats"></a>
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<p>
Next: <a href="Float-Arithmetic.html#Float-Arithmetic" accesskey="n" rel="next">Float Arithmetic</a>, Previous: <a href="Simultaneous-Float-Init-_0026-Assign.html#Simultaneous-Float-Init-_0026-Assign" accesskey="p" rel="prev">Simultaneous Float Init & Assign</a>, Up: <a href="Floating_002dpoint-Functions.html#Floating_002dpoint-Functions" accesskey="u" rel="up">Floating-point Functions</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Conversion-Functions-2"></a>
<h3 class="section">7.4 Conversion Functions</h3>
<a name="index-Float-conversion-functions"></a>
<a name="index-Conversion-functions-2"></a>
<dl>
<dt><a name="index-mpf_005fget_005fd"></a>Function: <em>double</em> <strong>mpf_get_d</strong> <em>(const mpf_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 in <var>op</var> 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-mpf_005fget_005fd_005f2exp"></a>Function: <em>double</em> <strong>mpf_get_d_2exp</strong> <em>(signed long int *<var>exp</var>, const mpf_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), and with an exponent returned separately.
</p>
<p>The return value is in the range <em>0.5<=abs(<var>d</var>)<1</em> and the
exponent is stored to <code>*<var>exp</var></code>. <em><var>d</var> * 2^<var>exp</var></em> is the (truncated) <var>op</var> value. If <var>op</var> is zero,
the return is <em>0.0</em> and 0 is stored to <code>*<var>exp</var></code>.
</p>
<a name="index-frexp-1"></a>
<p>This is similar to the standard C <code>frexp</code> function (see <a href="http://www.gnu.org/software/libc/manual/html_node/Normalization-Functions.html#Normalization-Functions">Normalization
Functions</a> in <cite>The GNU C Library Reference Manual</cite>).
</p></dd></dl>
<dl>
<dt><a name="index-mpf_005fget_005fsi"></a>Function: <em>long</em> <strong>mpf_get_si</strong> <em>(const mpf_t <var>op</var>)</em></dt>
<dt><a name="index-mpf_005fget_005fui"></a>Function: <em>unsigned long</em> <strong>mpf_get_ui</strong> <em>(const mpf_t <var>op</var>)</em></dt>
<dd><p>Convert <var>op</var> to a <code>long</code> or <code>unsigned long</code>, truncating any
fraction part. If <var>op</var> is too big for the return type, the result is
undefined.
</p>
<p>See also <code>mpf_fits_slong_p</code> and <code>mpf_fits_ulong_p</code>
(see <a href="Miscellaneous-Float-Functions.html#Miscellaneous-Float-Functions">Miscellaneous Float Functions</a>).
</p></dd></dl>
<dl>
<dt><a name="index-mpf_005fget_005fstr"></a>Function: <em>char *</em> <strong>mpf_get_str</strong> <em>(char *<var>str</var>, mp_exp_t *<var>expptr</var>, int <var>base</var>, size_t <var>n_digits</var>, const mpf_t <var>op</var>)</em></dt>
<dd><p>Convert <var>op</var> to a string of digits in base <var>base</var>. The base argument
may vary from 2 to 62 or from -2 to -36. Up to <var>n_digits</var>
digits will be generated. Trailing zeros are not returned. No more digits
than can be accurately represented by <var>op</var> are ever generated. If
<var>n_digits</var> is 0 then that accurate maximum number of digits are generated.
</p>
<p>For <var>base</var> in the range 2..36, digits and lower-case letters are used; for
-2..-36, digits and upper-case letters are used; for 37..62,
digits, upper-case letters, and lower-case letters (in that significance order)
are used.
</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
<em><var>n_digits</var> + 2</em> bytes, that being enough for the mantissa, a
possible minus sign, and a null-terminator. When <var>n_digits</var> is 0 to get
all significant digits, an application won’t be able to know the space
required, and <var>str</var> should be <code>NULL</code> in that case.
</p>
<p>The generated string is a fraction, with an implicit radix point immediately
to the left of the first digit. The applicable exponent is written through
the <var>expptr</var> pointer. For example, the number 3.1416 would be returned as
string <code>"31416"</code> and exponent 1.
</p>
<p>When <var>op</var> is zero, an empty string is produced and the exponent returned
is 0.
</p>
<p>A pointer to the result string is returned, being either the allocated block
or the given <var>str</var>.
</p></dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Float-Arithmetic.html#Float-Arithmetic" accesskey="n" rel="next">Float Arithmetic</a>, Previous: <a href="Simultaneous-Float-Init-_0026-Assign.html#Simultaneous-Float-Init-_0026-Assign" accesskey="p" rel="prev">Simultaneous Float Init & Assign</a>, Up: <a href="Floating_002dpoint-Functions.html#Floating_002dpoint-Functions" accesskey="u" rel="up">Floating-point Functions</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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