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    <section class="sect1" title="Numerical input and output" epub:type="subchapter" id="Numerical-input-and-output">
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          <div>
            <h2 class="title" style="clear: both">Numerical input and output</h2>
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      <p class="synopsis" kind="Procedure"><span class="kind">Procedure</span><span class="ignore">: </span><a id="idm139667876803392" class="indexterm"/> <code class="function">number-&gt;string</code> <em class="replaceable"><code>z</code></em> [<em class="replaceable"><code>radix</code></em>]</p>
      <div class="blockquote">
        <blockquote class="blockquote">
          <p>The procedure <code class="literal">number-&gt;string</code> takes a number and a
radix and returns as a string an external representation
of the given number in the given radix such that
</p>
          <pre class="screen">(let ((number number)
      (radix radix))
  (eqv? number
        (string-&gt;number (number-&gt;string number radix)
                        radix)))
</pre>
          <p>is true. It is an error if no possible result makes this expression true.
</p>
          <p>If present, <em class="replaceable"><code>radix</code></em> must be an exact integer
in the range 2 to 36, inclusive.
If omitted, <em class="replaceable"><code>radix</code></em> defaults to 10.
</p>
          <p>If <em class="replaceable"><code>z</code></em> is inexact, the <em class="replaceable"><code>radix</code></em> is 10, and the above expression
can be satisfied by a result that contains a decimal point,
then the result contains a decimal point and is expressed
using the minimum number of digits (exclusive of exponent
and trailing zeroes) needed to make the above expression;
otherwise the format of the result is unspecified.
</p>
          <p>The result returned by <code class="literal">number-&gt;string</code> never contains an
explicit radix prefix.
</p>
          <p><span class="emphasis"><em>Note:</em></span>
The error case can occur only when <em class="replaceable"><code>z</code></em> is not a complex
number or is a complex number with a non-rational real or
imaginary part.
</p>
          <p><span class="emphasis"><em>Rationale:</em></span> If <em class="replaceable"><code>z</code></em> is an inexact number and the <em class="replaceable"><code>radix</code></em> is 10,
then the above expression is normally satisfied by a result containing
a decimal point. The unspecified case allows for infinities, NaNs,
and unusual representations.
</p>
        </blockquote>
      </div>
      <p class="synopsis" kind="Procedure"><span class="kind">Procedure</span><span class="ignore">: </span><a id="idm139667876790832" class="indexterm"/> <code class="function">string-&gt;number</code> <em class="replaceable"><code>string</code></em> [<em class="replaceable"><code>radix</code></em>]</p>
      <div class="blockquote">
        <blockquote class="blockquote">
          <p>Returns a number of the maximally precise representation
expressed by the given <em class="replaceable"><code>string</code></em>. It is an error if <em class="replaceable"><code>radix</code></em> is not
an exact integer in the range 2 to 26, inclusive.
</p>
          <p>If supplied, <em class="replaceable"><code>radix</code></em> is a default radix that will be overridden
 if an explicit radix prefix is present in the string (e.g.
<code class="literal">"#o177"</code>). If <em class="replaceable"><code>radix</code></em> is not supplied, then the default <em class="replaceable"><code>radix</code></em>
is 10. If <em class="replaceable"><code>string</code></em> is not a syntactically valid notation for a
number, or would result in a number that the implementation cannot represent,
then <code class="literal">string-&gt;number</code> returns <code class="literal">#f</code>.
An error is never signaled due to the content of <em class="replaceable"><code>string</code></em>.
</p>
          <pre class="screen">(string-&gt;number "100")      ⇒  100
(string-&gt;number "100" 16)   ⇒  256
(string-&gt;number "1e2")      ⇒  100.0
(string-&gt;number "#x100" 10) ⇒  256
</pre>
        </blockquote>
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