正则表达式之PHP篇replace,filter,grep

<code> - preg\_replace( \$pattern,\$replacement,\$subject)，preg\_filter ( \$pattern,\$replacement,\$subject);
 preg\_replace 和preg\_filter 将匹配到的数值进行替换，可以使用数组替换;
\ $replacement 将匹配到的值替换为这个变量中存放的值;
 \$pattern正则表达式;
 \$subject返回结果；
</code>

<code><span><span>function</span><span>show</span><span>(<span>$var</span> = null)</span>{</span><span>if</span>(<span>empty</span>(<span>$var</span>)){
        <span>echo</span><span>'null'</span>;
    }<span>elseif</span>(is_array(<span>$var</span>)||is_object(<span>$var</span>)){
        <span>echo</span><span>'<pre class="brush:php;toolbar:false;">'</span>;
        print_r(<span>$var</span>);
        <span>echo</span><span>'<pre class="brush:php;toolbar:false;">'</span>;
    }<span>else</span> {
        <span>echo</span><span>$var</span>;
    }
}
<span>//preg_replace,preg_filter</span><span>//$pattern = '/[0-9]/';//字符串</span><span>$pattern</span> = <span>array</span>(<span>'/[0123]/'</span>,<span>'/[456]/'</span>,<span>'/[789]/'</span>);<span>//数组</span><span>//$subject = 'y1jp78yn16ww55j9';//是字符串，使用$pattern和$replacement作了一次匹配替换</span><span>$subject</span> = <span>array</span>(<span>'y'</span>,<span>'1jp78'</span>,<span>'yn'</span>,<span>'16ww'</span>,<span>'55j9'</span>);<span>//把$subject字符串任意拆分成好几段，放在$subject数组中，对数组中的每个值都做一次匹配替换</span><span>//$replacement = '慕女神';//当$subject匹配到结果后要替换的变量</span><span>$replacement</span> = <span>array</span>(<span>'慕'</span>,<span>'女'</span>,<span>'神'</span>);
<span>$str1</span> = preg_replace(<span>$pattern</span>,<span>$replacement</span>,<span>$subject</span>);<span>//保留所有字符串</span><span>$str2</span> = preg_filter(<span>$pattern</span>,<span>$replacement</span>,<span>$subject</span>);<span>//只会保留发生了替换的字符串</span>
show(<span>$str1</span>);
<span>echo</span><span>'<hr />'</span>;
show(<span>$str2</span>);</code>

<code>preg\_replace在数组匹配中会输出未发生匹配的字段;
preg\_filter 在数组匹配中不会输出未发生匹配的字段;
</code>