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Next: <a href="C_002b_002b-Interface-Limitations.html#C_002b_002b-Interface-Limitations" accesskey="n" rel="next">C++ Interface Limitations</a>, Previous: <a href="C_002b_002b-Interface-Floats.html#C_002b_002b-Interface-Floats" accesskey="p" rel="prev">C++ Interface Floats</a>, Up: <a href="C_002b_002b-Class-Interface.html#C_002b_002b-Class-Interface" accesskey="u" rel="up">C++ Class Interface</a> &nbsp; [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="C_002b_002b-Interface-Random-Numbers-1"></a>
<h3 class="section">12.5 C++ Interface Random Numbers</h3>
<dl>
<dt><a name="index-gmp_005frandclass"></a>Class: <strong>gmp_randclass</strong></dt>
<dd><p>The C++ class interface to the GMP random number functions uses
<code>gmp_randclass</code> to hold an algorithm selection and current state, as per
<code>gmp_randstate_t</code>.
</p></dd></dl>
<dl>
<dt><a name="index-gmp_005frandclass_003a_003agmp_005frandclass"></a>Function: <em></em> <strong>gmp_randclass::gmp_randclass</strong> <em>(void (*<var>randinit</var>) (gmp_randstate_t, &hellip;), &hellip;)</em></dt>
<dd><p>Construct a <code>gmp_randclass</code>, using a call to the given <var>randinit</var>
function (see <a href="Random-State-Initialization.html#Random-State-Initialization">Random State Initialization</a>). The arguments expected are
the same as <var>randinit</var>, but with <code>mpz_class</code> instead of <code>mpz_t</code>.
For example,
</p>
<div class="example">
<pre class="example">gmp_randclass r1 (gmp_randinit_default);
gmp_randclass r2 (gmp_randinit_lc_2exp_size, 32);
gmp_randclass r3 (gmp_randinit_lc_2exp, a, c, m2exp);
gmp_randclass r4 (gmp_randinit_mt);
</pre></div>
<p><code>gmp_randinit_lc_2exp_size</code> will fail if the size requested is too big,
an <code>std::length_error</code> exception is thrown in that case.
</p></dd></dl>
<dl>
<dt><a name="index-gmp_005frandclass_003a_003agmp_005frandclass-1"></a>Function: <em></em> <strong>gmp_randclass::gmp_randclass</strong> <em>(gmp_randalg_t <var>alg</var>, &hellip;)</em></dt>
<dd><p>Construct a <code>gmp_randclass</code> using the same parameters as
<code>gmp_randinit</code> (see <a href="Random-State-Initialization.html#Random-State-Initialization">Random State Initialization</a>). This function is
obsolete and the above <var>randinit</var> style should be preferred.
</p></dd></dl>
<dl>
<dt><a name="index-gmp_005frandclass_003a_003aseed"></a>Function: <em>void</em> <strong>gmp_randclass::seed</strong> <em>(unsigned long int <var>s</var>)</em></dt>
<dt><a name="index-gmp_005frandclass_003a_003aseed-1"></a>Function: <em>void</em> <strong>gmp_randclass::seed</strong> <em>(mpz_class <var>s</var>)</em></dt>
<dd><p>Seed a random number generator. See see <a href="Random-Number-Functions.html#Random-Number-Functions">Random Number Functions</a>, for how
to choose a good seed.
</p></dd></dl>
<dl>
<dt><a name="index-gmp_005frandclass_003a_003aget_005fz_005fbits"></a>Function: <em>mpz_class</em> <strong>gmp_randclass::get_z_bits</strong> <em>(mp_bitcnt_t <var>bits</var>)</em></dt>
<dt><a name="index-gmp_005frandclass_003a_003aget_005fz_005fbits-1"></a>Function: <em>mpz_class</em> <strong>gmp_randclass::get_z_bits</strong> <em>(mpz_class <var>bits</var>)</em></dt>
<dd><p>Generate a random integer with a specified number of bits.
</p></dd></dl>
<dl>
<dt><a name="index-gmp_005frandclass_003a_003aget_005fz_005frange"></a>Function: <em>mpz_class</em> <strong>gmp_randclass::get_z_range</strong> <em>(mpz_class <var>n</var>)</em></dt>
<dd><p>Generate a random integer in the range 0 to <em><var>n</var>-1</em> inclusive.
</p></dd></dl>
<dl>
<dt><a name="index-gmp_005frandclass_003a_003aget_005ff"></a>Function: <em>mpf_class</em> <strong>gmp_randclass::get_f</strong> <em>()</em></dt>
<dt><a name="index-gmp_005frandclass_003a_003aget_005ff-1"></a>Function: <em>mpf_class</em> <strong>gmp_randclass::get_f</strong> <em>(mp_bitcnt_t <var>prec</var>)</em></dt>
<dd><p>Generate a random float <var>f</var> in the range <em>0 &lt;= <var>f</var> &lt; 1</em>. <var>f</var>
will be to <var>prec</var> bits precision, or if <var>prec</var> is not given then to
the precision of the destination. For example,
</p>
<div class="example">
<pre class="example">gmp_randclass r;
...
mpf_class f (0, 512); // 512 bits precision
f = r.get_f(); // random number, 512 bits
</pre></div>
</dd></dl>
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Next: <a href="C_002b_002b-Interface-Limitations.html#C_002b_002b-Interface-Limitations" accesskey="n" rel="next">C++ Interface Limitations</a>, Previous: <a href="C_002b_002b-Interface-Floats.html#C_002b_002b-Interface-Floats" accesskey="p" rel="prev">C++ Interface Floats</a>, Up: <a href="C_002b_002b-Class-Interface.html#C_002b_002b-Class-Interface" accesskey="u" rel="up">C++ Class Interface</a> &nbsp; [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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