mirror of
https://github.com/fofolee/uTools-Manuals.git
synced 2025-06-19 06:16:58 +08:00
337 lines
16 KiB
HTML
337 lines
16 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
<html>
|
||
<head>
|
||
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
|
||
<title>从数组中将变量导入到当前的符号表</title>
|
||
</head>
|
||
<body class="docs"><div id="layout">
|
||
<div id="layout-content"><div id="function.extract" class="refentry">
|
||
<div class="refnamediv">
|
||
<h1 class="refname">extract</h1>
|
||
<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">extract</span> — <span class="dc-title">从数组中将变量导入到当前的符号表</span></p>
|
||
|
||
</div>
|
||
<div class="refsect1 description" id="refsect1-function.extract-description">
|
||
<h3 class="title">说明</h3>
|
||
<div class="methodsynopsis dc-description">
|
||
<span class="methodname"><strong>extract</strong></span>
|
||
( <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$array</code></span>
|
||
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$flags</code><span class="initializer"> = EXTR_OVERWRITE</span></span>
|
||
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$prefix</code><span class="initializer"> = <strong><code>NULL</code></strong></span></span>
|
||
]] ) : <span class="type">int</span></div>
|
||
|
||
<p class="para rdfs-comment">
|
||
本函数用来将变量从数组中导入到当前的符号表中。
|
||
</p>
|
||
<p class="para">
|
||
检查每个键名看是否可以作为一个合法的变量名，同时也检查和符号表中已有的变量名的冲突。
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 parameters" id="refsect1-function.extract-parameters">
|
||
<h3 class="title">参数</h3>
|
||
<p class="para">
|
||
<dl>
|
||
|
||
|
||
<dt>
|
||
<code class="parameter">array</code></dt>
|
||
|
||
<dd>
|
||
|
||
<p class="para">
|
||
一个关联数组。此函数会将键名当作变量名，值作为变量的值。
|
||
对每个键／值对都会在当前的符号表中建立变量，并受到
|
||
<code class="parameter">flags</code> 和 <code class="parameter">prefix</code> 参数的影响。
|
||
</p>
|
||
<p class="para">
|
||
必须使用关联数组，数字索引的数组将不会产生结果，除非用了
|
||
<strong><code>EXTR_PREFIX_ALL</code></strong> 或者 <strong><code>EXTR_PREFIX_INVALID</code></strong>。
|
||
</p>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<code class="parameter">flags</code></dt>
|
||
|
||
<dd>
|
||
|
||
<p class="para">
|
||
对待非法／数字和冲突的键名的方法将根据取出标记
|
||
<code class="parameter">flags</code> 参数决定。可以是以下值之一：
|
||
<dl>
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_OVERWRITE</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
如果有冲突，覆盖已有的变量。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_SKIP</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
如果有冲突，不覆盖已有的变量。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_PREFIX_SAME</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">如果有冲突，在变量名前加上前缀 <code class="parameter">prefix</code>。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_PREFIX_ALL</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
给所有变量名加上前缀
|
||
<code class="parameter">prefix</code>。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_PREFIX_INVALID</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
仅在非法／数字的变量名前加上前缀 <code class="parameter">prefix</code>。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_IF_EXISTS</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
仅在当前符号表中已有同名变量时，覆盖它们的值。其它的都不处理。
|
||
举个例子，以下情况非常有用：定义一些有效变量，然后从 <var class="varname"><var class="varname"><a href="reserved.variables.request.html" class="classname">$_REQUEST</a></var></var> 中仅导入这些已定义的变量。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_PREFIX_IF_EXISTS</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
仅在当前符号表中已有同名变量时，建立附加了前缀的变量名，其它的都不处理。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<strong><code>EXTR_REFS</code></strong></dt>
|
||
|
||
<dd>
|
||
|
||
<span class="simpara">
|
||
将变量作为引用提取。这有力地表明了导入的变量仍然引用了
|
||
<code class="parameter">array</code> 参数的值。可以单独使用这个标志或者在
|
||
<code class="parameter">flags</code> 中用 OR 与其它任何标志结合使用。
|
||
</span>
|
||
</dd>
|
||
|
||
|
||
</dl>
|
||
|
||
</p>
|
||
<p class="para">
|
||
如果没有指定 <code class="parameter">flags</code>，则被假定为 <strong><code>EXTR_OVERWRITE</code></strong>。
|
||
</p>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<code class="parameter">prefix</code></dt>
|
||
|
||
<dd>
|
||
|
||
<p class="para">
|
||
注意 <code class="parameter">prefix</code> 仅在
|
||
<code class="parameter">flags</code> 的值是
|
||
<strong><code>EXTR_PREFIX_SAME</code></strong>，<strong><code>EXTR_PREFIX_ALL</code></strong>，<strong><code>EXTR_PREFIX_INVALID</code></strong>
|
||
或 <strong><code>EXTR_PREFIX_IF_EXISTS</code></strong>
|
||
时需要。
|
||
如果附加了前缀后的结果不是合法的变量名，将不会导入到符号表中。前缀和数组键名之间会自动加上一个下划线。
|
||
</p>
|
||
</dd>
|
||
|
||
|
||
</dl>
|
||
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 returnvalues" id="refsect1-function.extract-returnvalues">
|
||
<h3 class="title">返回值</h3>
|
||
<p class="para">
|
||
返回成功导入到符号表中的变量数目。
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 examples" id="refsect1-function.extract-examples">
|
||
<h3 class="title">范例</h3>
|
||
<p class="para">
|
||
<div class="example" id="example-6096">
|
||
<p><strong>Example #1 <span class="function"><strong>extract()</strong></span> 例子</strong></p>
|
||
<div class="example-contents"><p>
|
||
<span class="function"><strong>extract()</strong></span> 的一种可能用法是将 <span class="function"><a href="wddx_deserialize.html" class="function">wddx_deserialize()</a></span>
|
||
返回的结合数组中的内容导入到符号表变量中去。
|
||
</p></div>
|
||
<div class="example-contents">
|
||
<div class="phpcode"><pre><span style="color: #000000">
|
||
<span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">/* 假定 $var_array 是 wddx_deserialize 返回的数组*/<br /><br /></span><span style="color: #0000BB">$size </span><span style="color: #007700">= </span><span style="color: #DD0000">"large"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$var_array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"color" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"blue"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"size" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"medium"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"shape" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"sphere"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">extract</span><span style="color: #007700">(</span><span style="color: #0000BB">$var_array</span><span style="color: #007700">, </span><span style="color: #0000BB">EXTR_PREFIX_SAME</span><span style="color: #007700">, </span><span style="color: #DD0000">"wddx"</span><span style="color: #007700">);<br /><br />echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$color</span><span style="color: #DD0000">, </span><span style="color: #0000BB">$size</span><span style="color: #DD0000">, </span><span style="color: #0000BB">$shape</span><span style="color: #DD0000">, </span><span style="color: #0000BB">$wddx_size</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">?></span>
|
||
</span>
|
||
</pre></div>
|
||
</div>
|
||
|
||
<div class="example-contents"><p>以上例程会输出：</p></div>
|
||
<div class="example-contents screen">
|
||
<div class="cdata"><pre>
|
||
blue, large, sphere, medium
|
||
</pre></div>
|
||
</div>
|
||
<div class="example-contents"><p>
|
||
<var class="varname"><var class="varname">$size</var></var> 没有被覆盖，因为指定了
|
||
<strong><code>EXTR_PREFIX_SAME</code></strong>，这使得 <var class="varname"><var class="varname">$wddx_size</var></var>
|
||
被建立。如果指定了 <strong><code>EXTR_SKIP</code></strong>，则 <var class="varname"><var class="varname">$wddx_size</var></var>
|
||
也不会被建立。<strong><code>EXTR_OVERWRITE</code></strong> 将使 <var class="varname"><var class="varname">$size</var></var>
|
||
的值为“medium”，<strong><code>EXTR_PREFIX_ALL</code></strong> 将建立新变量
|
||
<var class="varname"><var class="varname">$wddx_color</var></var>，<var class="varname"><var class="varname">$wddx_size</var></var> 和
|
||
<var class="varname"><var class="varname">$wddx_shape</var></var>。
|
||
</p></div>
|
||
</div>
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 notes" id="refsect1-function.extract-notes">
|
||
<h3 class="title">注释</h3>
|
||
<div class="warning"><strong class="warning">Warning</strong>
|
||
<p class="para">
|
||
不要对不能信任的数据使用
|
||
<span class="function"><strong>extract()</strong></span>，例如用户的输入（<var class="varname"><var class="varname"><a href="reserved.variables.get.html" class="classname">$_GET</a></var></var>， <var class="varname"><var class="varname"><a href="reserved.variables.files.html" class="classname">$_FILES</a></var></var>，...）。如果这样做，举例说，要临时运行依赖于
|
||
<a href="security.globals.html" class="link">register_globals</a>
|
||
的老代码，要确保使用不会覆盖的
|
||
<code class="parameter">extract_type</code> 值，例如
|
||
<strong><code>EXTR_SKIP</code></strong>，并且要留意应该按照 <a href="ini.core.html#ini.variables_order" class="link">variables_order</a> 在 <a href="ini.html" class="link"><var class="filename">php.ini</var></a> 里
|
||
定义的顺序来提取。
|
||
</p>
|
||
</div>
|
||
<blockquote class="note"><p><strong class="note">Note</strong>:
|
||
<p class="para">
|
||
If you still
|
||
have <a href="security.globals.html" class="link">register_globals</a>
|
||
and it is turned on, if you use <span class="function"><strong>extract()</strong></span>
|
||
on <var class="varname"><var class="varname"><a href="reserved.variables.files.html" class="classname">$_FILES</a></var></var> and
|
||
specify <strong><code>EXTR_SKIP</code></strong>, you may be surprised at
|
||
the results.
|
||
</p>
|
||
<div class="warning"><strong class="warning">Warning</strong>
|
||
<p class="para">
|
||
This is not recommended practice and is only documented here for
|
||
completeness. The use
|
||
of <a href="security.globals.html" class="link">register_globals</a> is
|
||
deprecated and calling <span class="function"><strong>extract()</strong></span> on untrusted
|
||
data such as <var class="varname"><var class="varname"><a href="reserved.variables.files.html" class="classname">$_FILES</a></var></var> is, as noted above, a
|
||
potential security risk. If you encounter this issue, it means
|
||
that you are using at least two poor coding practices.
|
||
</p>
|
||
</div>
|
||
<div class="example-contents">
|
||
<div class="phpcode"><pre><span style="color: #000000">
|
||
<span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">/* Suppose that $testfile is the name of a file upload input<br /> and that register_globals is turned on. */<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$testfile</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">extract</span><span style="color: #007700">(</span><span style="color: #0000BB">$_FILES</span><span style="color: #007700">, </span><span style="color: #0000BB">EXTR_SKIP</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$testfile</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$testfile</span><span style="color: #007700">[</span><span style="color: #DD0000">'tmp_name'</span><span style="color: #007700">]);<br /><br /></span><span style="color: #0000BB">?></span>
|
||
</span>
|
||
</pre></div>
|
||
</div>
|
||
|
||
<span class="simpara">
|
||
You might expect to see something like the following:
|
||
</span>
|
||
<div class="example-contents screen">
|
||
<div class="cdata"><pre>
|
||
string(14) "/tmp/phpgCCPX8"
|
||
array(5) {
|
||
["name"]=>
|
||
string(10) "somefile.txt"
|
||
["type"]=>
|
||
string(24) "application/octet-stream"
|
||
["tmp_name"]=>
|
||
string(14) "/tmp/phpgCCPX8"
|
||
["error"]=>
|
||
int(0)
|
||
["size"]=>
|
||
int(4208)
|
||
}
|
||
string(14) "/tmp/phpgCCPX8"
|
||
</pre></div>
|
||
</div>
|
||
<span class="simpara">
|
||
However, you would instead see something like this:
|
||
</span>
|
||
<div class="example-contents screen">
|
||
<div class="cdata"><pre>
|
||
string(14) "/tmp/phpgCCPX8"
|
||
string(14) "/tmp/phpgCCPX8"
|
||
string(1) "/"
|
||
</pre></div>
|
||
</div>
|
||
<p class="para">
|
||
This is due to the fact that
|
||
since <a href="security.globals.html" class="link">register_globals</a> is
|
||
turned on, <var class="varname"><var class="varname">$testfile</var></var> already exists in the
|
||
global scope when <span class="function"><strong>extract()</strong></span> is called. And
|
||
since <strong><code>EXTR_SKIP</code></strong> is
|
||
specified, <var class="varname"><var class="varname">$testfile</var></var> is not overwritten with
|
||
the contents of the <strong><code>$_FILES</code></strong> array
|
||
so <var class="varname"><var class="varname">$testfile</var></var> remains a string.
|
||
Because <a href="language.types.string.html#language.types.string.substr" class="link">strings may
|
||
be accessed using array syntax</a> and the non-numeric string
|
||
<em>tmp_name</em> is interpreted
|
||
as <em>0</em>, PHP
|
||
sees <var class="varname"><var class="varname">$testfile['tmp_name']</var></var>
|
||
as <var class="varname"><var class="varname">$testfile[0]</var></var>.
|
||
</p>
|
||
</p></blockquote>
|
||
</div>
|
||
|
||
<div class="refsect1 seealso" id="refsect1-function.extract-seealso">
|
||
<h3 class="title">参见</h3>
|
||
<p class="para">
|
||
<ul class="simplelist">
|
||
<li class="member"><span class="function"><a href="compact.html" class="function" rel="rdfs-seeAlso">compact()</a> - 建立一个数组，包括变量名和它们的值</span></li>
|
||
<li class="member"><span class="function"><a href="list.html" class="function" rel="rdfs-seeAlso">list()</a> - 把数组中的值赋给一组变量</span></li>
|
||
</ul>
|
||
</p>
|
||
</div>
|
||
|
||
</div></div></div></body></html> |