<?xml version="1.0" encoding="utf-8"?>

<!-- $Revision$ -->

<!-- EN-Revision: 761d72245071f89a626903c9bcdc6aaff1252d54 Maintainer: dallas Status: ready -->

<!-- CREDITS: mowangjuanzi, Luffy -->

<refentry xml:id="function.pow" xmlns="http://docbook.org/ns/docbook">

<refnamediv>

<refname>pow</refname>

<refpurpose>指数表达式</refpurpose>

</refnamediv>

<refsect1 role="description">

&reftitle.description;

<methodsynopsis>

<type class="union"><type>int</type><type>float</type><type>object</type></type><methodname>pow</methodname>

<methodparam><type>mixed</type><parameter>num</parameter></methodparam>

<methodparam><type>mixed</type><parameter>exponent</parameter></methodparam>

</methodsynopsis>

<para>

返回 <parameter>num</parameter> 的 <parameter>exponent</parameter> 次方的幂。

</para>

<note>

<para>

可以使用 <link linkend="language.operators.arithmetic">**</link> 运算符代替。

</para>

</note>

</refsect1>

<refsect1 role="parameters">

&reftitle.parameters;

<para>

<variablelist>

<varlistentry>

<term><parameter>num</parameter></term>

<listitem>

<para>

底数

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><parameter>exponent</parameter></term>

<listitem>

<para>

指数

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

</refsect1>

<refsect1 role="returnvalues">

&reftitle.returnvalues;

<para>

<parameter>num</parameter> 的 <parameter>exponent</parameter>

次方。如果两个参数都是非负整数且结果可以用整数表示，则返回 <type>int</type>

类型，否则返回 <type>float</type>。

</para>

<para>

PHP 扩展可能会覆盖此操作的行为，使其返回一个对象。

</para>

</refsect1>

<refsect1 role="examples">

&reftitle.examples;

<para>

<example>

<title><function>pow</function> 的一些示例</title>

<programlisting role="php">

<![CDATA[

<?php

var_dump(pow(2, 8)); // int(256)

echo pow(-1, 20), PHP_EOL; // 1

echo pow(0, 0), PHP_EOL; // 1

echo pow(10, -1), PHP_EOL; // 0.1

echo pow(-1, 5.5), PHP_EOL; // NAN

?>

]]>

</programlisting>

</example>

</para>

<para>

<example>

<title>Examples of <function>pow</function> With GMP Extension Object</title>

<programlisting role="php" annotations="non-interactive">

<![CDATA[

<?php

var_dump(pow(new GMP("3"), new GMP("2"))); // object(GMP)

?>

]]>

</programlisting>

</example>

</para>

</refsect1>

<refsect1 role="notes">

&reftitle.notes;

<note>

<para>

本函数会转换所有输入为数字，甚至是非标量值，将会导致<emphasis>怪异的</emphasis>结果。

</para>

</note>

</refsect1>

<refsect1 role="seealso">

&reftitle.seealso;

<para>

<simplelist>

<member><function>exp</function></member>

<member><function>sqrt</function></member>

<member><function>bcpow</function></member>

<member><function>gmp_pow</function></member>

</simplelist>

</para>

</refsect1>

</refentry>

<!-- Keep this comment at the end of the file

Local variables:

mode: sgml

sgml-omittag:t

sgml-shorttag:t

sgml-minimize-attributes:nil

sgml-always-quote-attributes:t

sgml-indent-step:1

sgml-indent-data:t

indent-tabs-mode:nil

sgml-parent-document:nil

sgml-default-dtd-file:"~/.phpdoc/manual.ced"

sgml-exposed-tags:nil

sgml-local-catalogs:nil

sgml-local-ecat-files:nil

End:

vim600: syn=xml fen fdm=syntax fdl=2 si

vim: et tw=78 syn=sgml

vi: ts=1 sw=1

-->