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260 lines
9.3 KiB
HTML
260 lines
9.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>Unpack data from binary string</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.unpack" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">unpack</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">unpack</span> — <span class="dc-title">Unpack data from binary string</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.unpack-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>unpack</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$format</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$data</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$offset</code><span class="initializer"> = 0</span></span>
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] ) : <span class="type">array</span></div>
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<p class="para rdfs-comment">
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Unpacks from a binary string into an array according to the given
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<code class="parameter">format</code>.
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</p>
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<p class="para">
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The unpacked data is stored in an associative array. To
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accomplish this you have to name the different format codes and
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separate them by a slash /. If a repeater argument is present,
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then each of the array keys will have a sequence number behind
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the given name.
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.unpack-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">format</code></dt>
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<dd>
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<p class="para">
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See <span class="function"><a href="pack.html" class="function">pack()</a></span> for an explanation of the format codes.
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</p>
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</dd>
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<dt>
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<code class="parameter">data</code></dt>
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<dd>
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<p class="para">
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The packed data.
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</p>
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</dd>
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<dt>
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<code class="parameter">offset</code></dt>
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<dd>
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<p class="para">
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The offset to begin unpacking from.
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.unpack-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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Returns an associative array containing unpacked elements of binary
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string.
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.unpack-changelog">
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<h3 class="title">更新日志</h3>
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<p class="para">
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<table class="doctable informaltable">
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<thead>
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<tr>
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<th>版本</th>
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<th>说明</th>
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</tr>
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</thead>
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<tbody class="tbody">
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<tr>
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<td>7.2.0</td>
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<td>
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<span class="type"><a href="language.types.float.html" class="type float">float</a></span> and <span class="type"><a href="language.types.float.html" class="type double">double</a></span> types supports both Big Endian and Little Endian.
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</td>
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</tr>
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<tr>
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<td>7.1.0</td>
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<td>
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The optional <code class="parameter">offset</code> has been added.
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</td>
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</tr>
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<tr>
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<td>5.5.0</td>
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<td>
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<p class="para">
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Changes were made to bring this function into line with Perl:
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</p>
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<p class="para">
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The "a" code now retains trailing NULL bytes.
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</p>
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<p class="para">
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The "A" code now strips all trailing ASCII whitespace (spaces, tabs,
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newlines, carriage returns, and NULL bytes).
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</p>
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<p class="para">
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The "Z" code was added for NULL-padded strings, and removes trailing
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NULL bytes.
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</p>
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</td>
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</tr>
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</tbody>
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</table>
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.unpack-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-4553">
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<p><strong>Example #1 <span class="function"><strong>unpack()</strong></span> example</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$binarydata </span><span style="color: #007700">= </span><span style="color: #DD0000">"\x04\x00\xa0\x00"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$array </span><span style="color: #007700">= </span><span style="color: #0000BB">unpack</span><span style="color: #007700">(</span><span style="color: #DD0000">"cchars/nint"</span><span style="color: #007700">, </span><span style="color: #0000BB">$binarydata</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Array
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(
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[chars] => 4
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[int] => 160
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)
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-4554">
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<p><strong>Example #2 <span class="function"><strong>unpack()</strong></span> example with a repeater</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$binarydata </span><span style="color: #007700">= </span><span style="color: #DD0000">"\x04\x00\xa0\x00"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$array </span><span style="color: #007700">= </span><span style="color: #0000BB">unpack</span><span style="color: #007700">(</span><span style="color: #DD0000">"c2chars/nint"</span><span style="color: #007700">, </span><span style="color: #0000BB">$binarydata</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Array
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(
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[chars1] => 4
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[chars2] => 0
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[int] => 40960
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)
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.unpack-notes">
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<h3 class="title">注释</h3>
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<div class="caution"><strong class="caution">Caution</strong>
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<p class="para">
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Note that PHP internally stores integral values as signed. If you
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unpack a large unsigned long and it is of the same size as PHP
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internally stored values the result will be a negative number
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even though unsigned unpacking was specified.
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</p>
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</div>
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<div class="caution"><strong class="caution">Caution</strong>
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<p class="para">
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If you do not name an element, numeric indices starting from <em>1</em> are used.
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Be aware that if you have more than one unnamed element, some data is
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overwritten because the numbering restarts from <em>1</em> for each element.
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</p>
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<p class="para">
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<div class="example" id="example-4555">
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<p><strong>Example #3 <span class="function"><strong>unpack()</strong></span> example with unnamed keys</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$binarydata </span><span style="color: #007700">= </span><span style="color: #DD0000">"\x32\x42\x00\xa0"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$array </span><span style="color: #007700">= </span><span style="color: #0000BB">unpack</span><span style="color: #007700">(</span><span style="color: #DD0000">"c2/n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$binarydata</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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array(2) {
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[1]=>
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int(160)
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[2]=>
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int(66)
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}
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</pre></div>
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</div>
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<div class="example-contents"><p>
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Note that the
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first value from the <em>c</em> specifier is
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overwritten by the first value from the <em>n</em>
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specifier.
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</p></div>
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</div>
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</p>
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</div>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.unpack-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="pack.html" class="function" rel="rdfs-seeAlso">pack()</a> - 将数据打包成二进制字符串</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |