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<title>2.4.5 Floating point literals</title>
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<H2><A NAME="SECTION004450000000000000000"></A><A NAME="floating"></A>
<BR>
2.4.5 Floating point literals
</H2>

<P>
Floating point literals are described by the following lexical
definitions:

<P>
<dl><dd class="grammar">
<div class="productions">
<table>
<tr>
    <td><a id='tok-floatnumber' xml:id='tok-floatnumber'>floatnumber</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="floating.html#tok-pointfloat">pointfloat</a> | <a class='grammartoken' href="floating.html#tok-exponentfloat">exponentfloat</a></td></tr>
  <tr>
    <td><a id='tok-pointfloat' xml:id='tok-pointfloat'>pointfloat</a></td>
    <td>::=</td>
    <td>[<a class='grammartoken' href="floating.html#tok-intpart">intpart</a>] <a class='grammartoken' href="floating.html#tok-fraction">fraction</a> | <a class='grammartoken' href="floating.html#tok-intpart">intpart</a> "."</td></tr>
  <tr>
    <td><a id='tok-exponentfloat' xml:id='tok-exponentfloat'>exponentfloat</a></td>
    <td>::=</td>
    <td>(<a class='grammartoken' href="floating.html#tok-intpart">intpart</a> | <a class='grammartoken' href="floating.html#tok-pointfloat">pointfloat</a>)
              <a class='grammartoken' href="floating.html#tok-exponent">exponent</a></td></tr>
  <tr>
    <td><a id='tok-intpart' xml:id='tok-intpart'>intpart</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="identifiers.html#tok-digit">digit</a>+</td></tr>
  <tr>
    <td><a id='tok-fraction' xml:id='tok-fraction'>fraction</a></td>
    <td>::=</td>
    <td>"." <a class='grammartoken' href="identifiers.html#tok-digit">digit</a>+</td></tr>
  <tr>
    <td><a id='tok-exponent' xml:id='tok-exponent'>exponent</a></td>
    <td>::=</td>
    <td>("e" | "E") ["+" | "-"] <a class='grammartoken' href="identifiers.html#tok-digit">digit</a>+</td></tr>
</table>
</div>
<a class="grammar-footer"
  href="grammar.txt" type="text/plain"
  >Download entire grammar as text.</a>
</dd></dl>

<P>
Note that the integer and exponent parts of floating point numbers
can look like octal integers, but are interpreted using radix 10.  For
example, "<tt class="samp">077e010</tt>" is legal, and denotes the same number
as "<tt class="samp">77e10</tt>".
The allowed range of floating point literals is
implementation-dependent.
Some examples of floating point literals:

<P>
<div class="verbatim"><pre>
3.14    10.    .001    1e100    3.14e-10    0e0
</pre></div>

<P>
Note that numeric literals do not include a sign; a phrase like
<code>-1</code> is actually an expression composed of the operator
<code>-</code> and the literal <code>1</code>.

<P>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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