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>preg_replace_callback</H1
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><P
> (PHP 4 >= 4.0.5, PHP 5)</P
>preg_replace_callback -- 用回调函数执行正则表达式的搜索和替换</DIV
><DIV
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><H2
>说明</H2
>mixed <B
CLASS="methodname"
>preg_replace_callback</B
> ( mixed pattern, callback callback, mixed subject [, int limit] )<BR
></BR
><P
> 本函数的行为几乎和
<A
HREF="function.preg-replace.html"
><B
CLASS="function"
>preg_replace()</B
></A
> 一样，除了不是提供一个
<CODE
CLASS="parameter"
>replacement</CODE
> 参数，而是指定一个
<CODE
CLASS="parameter"
>callback</CODE
> 函数。该函数将以目标字符串中的匹配数组作为输入参数，并返回用于替换的字符串。
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><B
>例 1. <B
CLASS="function"
>preg_replace_callback()</B
> 例子</B
></P
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><code><font color="#000000">
<font color="#0000BB"><?php<br /> </font><font color="#FF8000">// 此文本是用于 2002 年的，<br /> // 现在想使其能用于 2003 年<br /> </font><font color="#0000BB">$text </font><font color="#007700">= </font><font color="#DD0000">"April fools day is 04/01/2002\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">$text</font><font color="#007700">.= </font><font color="#DD0000">"Last christmas was 12/24/2001\n"</font><font color="#007700">;<br /><br /> </font><font color="#FF8000">// 回调函数<br /> </font><font color="#007700">function </font><font color="#0000BB">next_year</font><font color="#007700">(</font><font color="#0000BB">$matches</font><font color="#007700">) {<br /> </font><font color="#FF8000">// 通常：$matches[0] 是完整的匹配项<br /> // $matches[1] 是第一个括号中的子模式的匹配项<br /> // 以此类推<br /> </font><font color="#007700">return </font><font color="#0000BB">$matches</font><font color="#007700">[</font><font color="#0000BB">1</font><font color="#007700">].(</font><font color="#0000BB">$matches</font><font color="#007700">[</font><font color="#0000BB">2</font><font color="#007700">]+</font><font color="#0000BB">1</font><font color="#007700">);<br /> }<br /><br /> echo </font><font color="#0000BB">preg_replace_callback</font><font color="#007700">(<br /> </font><font color="#DD0000">"|(\d{2}/\d{2}/)(\d{4})|"</font><font color="#007700">,<br /> </font><font color="#DD0000">"next_year"</font><font color="#007700">,<br /> </font><font color="#0000BB">$text</font><font color="#007700">);<br /><br /> </font><font color="#FF8000">// 结果为：<br /> // April fools day is 04/01/2003<br /> // Last christmas was 12/24/2002<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
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><P
> You'll often need the <CODE
CLASS="parameter"
>callback</CODE
> function
for a <B
CLASS="function"
>preg_replace_callback()</B
> in just one place.
In this case you can use <A
HREF="function.create-function.html"
><B
CLASS="function"
>create_function()</B
></A
> to
declare an anonymous function as callback within the call to
<B
CLASS="function"
>preg_replace_callback()</B
>. By doing it this way
you have all information for the call in one place and do not
clutter the function namespace with a callback functions name
not used anywhere else.
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><B
>例 2. <B
CLASS="function"
>preg_replace_callback()</B
> 和 <A
HREF="function.create-function.html"
><B
CLASS="function"
>create_function()</B
></A
></B
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><code><font color="#000000">
<font color="#0000BB"><?php<br /> </font><font color="#FF8000">/* 一个 UNIX 风格的命令行过滤器，将每个段落开头的<br /> * 大写字母转换成小写字母 */<br /><br /> </font><font color="#0000BB">$fp </font><font color="#007700">= </font><font color="#0000BB">fopen</font><font color="#007700">(</font><font color="#DD0000">"php://stdin"</font><font color="#007700">, </font><font color="#DD0000">"r"</font><font color="#007700">) or die(</font><font color="#DD0000">"can't read stdin"</font><font color="#007700">);<br /> while (!</font><font color="#0000BB">feof</font><font color="#007700">(</font><font color="#0000BB">$fp</font><font color="#007700">)) {<br /> </font><font color="#0000BB">$line </font><font color="#007700">= </font><font color="#0000BB">fgets</font><font color="#007700">(</font><font color="#0000BB">$fp</font><font color="#007700">);<br /> </font><font color="#0000BB">$line </font><font color="#007700">= </font><font color="#0000BB">preg_replace_callback</font><font color="#007700">(<br /> </font><font color="#DD0000">'|<p>\s*\w|'</font><font color="#007700">,<br /> </font><font color="#0000BB">create_function</font><font color="#007700">(<br /> </font><font color="#FF8000">// 这里使用单引号很关键，<br /> // 否则就把所有的 $ 换成 \$<br /> </font><font color="#DD0000">'$matches'</font><font color="#007700">,<br /> </font><font color="#DD0000">'return strtolower($matches[0]);'<br /> </font><font color="#007700">),<br /> </font><font color="#0000BB">$line<br /> </font><font color="#007700">);<br /> echo </font><font color="#0000BB">$line</font><font color="#007700">;<br /> }<br /> </font><font color="#0000BB">fclose</font><font color="#007700">(</font><font color="#0000BB">$fp</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
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><P
> 参见 <A
HREF="function.preg-replace.html"
><B
CLASS="function"
>preg_replace()</B
></A
> 和
<A
HREF="function.create-function.html"
><B
CLASS="function"
>create_function()</B
></A
>。
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