Summary of php regular expression examples

1. 根据购物车中的商品Item ID，准确判断客人的原装机型号。

<?php
    $title = "Replacement Canon BP-511 Camcorder Battery [Item ID:3-236-523]";
    if( eregi("(\[Item ID:)([0-9]+)-([0-9]+)-([0-9]+)(])",$title,$arr) ){
        echo "<pre class="brush:php;toolbar:false">";
        print_r($arr);
        echo "

"; } ?>

2.匹配日期

<?php
    // 分隔符可以是斜线，点，或横线
    $date = "04/30/1973";
    list($month, $day, $year) = split (&#39;[/.-]&#39;, $date); // 漏洞: 04/30-1973也能匹配得上
    echo "Month: $month; Day: $day; Year: $year<br />\n";
?>

3. 搜索单词 web

<?phpif (preg_match ("/\bweb\b/i", "PHP is the website scripting language of choice.")) {    print "A match was found.";} else {    print "A match was not found.";}?>

4. 从url 中取出域名

<?php
    // 从 URL 中取得主机名
    preg_match("/^(http:\/\/)?([^\/]+)/i",
        "http://www.php.net/index.html", $matches);
    $host = $matches[2];
    // 从主机名中取得后面两段
    preg_match("/[^\.\/]+\.[^\.\/]+$/", $host, $matches);
    echo "domain name is: {$matches[0]}\n";
    // 本例执行后将输出: domain name is: php.net
?>

5. 你知道下面的程序输出什么?

<?php
    preg_match_all ("|<[^>]+>(.*)</[^>]+>|U",
        "<b>example: </b><div align=left>this is a test</div>",
        $out, PREG_PATTERN_ORDER); // 注意PREG_PATTERN_ORDER和PREG_SET_ORDER的区别
    print $out[0][0].", ".$out[0][1]."\n";
    print $out[1][0].", ".$out[1][1]."\n";
    echo "<pre class="brush:php;toolbar:false">";
    print_r($out);
?>

6. 功能: 转义正则表达式字符，此函数很有用，可以供你写正则表达式时参考

<?php
    $keywords = "$40 for a g3/400";
    $keywords = preg_quote ($keywords, "/");
    echo $keywords; // returns \$40 for a g3\/400
?>

7. 看人家如何用 preg_quote() 函数实现高亮显示

<?php
    // 本例中，preg_quote($word) 用来使星号不在正则表达式中
    // 具有特殊含义。
    $textbody = "This book is *very* difficult to find.";
    $word = "*very*";
    $textbody = preg_replace ("/".preg_quote($word)."/","<b>".$word."</b>",$textbody);
    echo $textbody;
?>

8. 用回调函数执行正则表达式的搜索和替换

<?php  
    // 此文本是用于 2002 年的，  
    // 现在想使其能用于 2003 年  
    $text = "April fools day is 04/01/2002\n";  
    $text.= "Last christmas was 12/24/2001\n";  
    // 回调函数  
    function next_year($matches) {    
    // 通常：$matches[0] 是完整的匹配项    
    // $matches[1] 是第一个括号中的子模式的匹配项    
    // 以此类推
      
     return $matches[1].($matches[2]+1);  
     }  
     echo preg_replace_callback("|(\d{2}/\d{2}/)(\d{4})|","next_year",$text);  
     // 结果为：  
     // April fools day is 04/01/2003  
     // Last christmas was 12/24/2002
 ?>

9. 在 preg_replace() 中使用索引数组

<?php
    $string = "The quick brown fox jumped over the lazy dog.";
    $patterns[0] = "/quick/";
    $patterns[1] = "/brown/";
    $patterns[2] = "/fox/";
    $replacements[2] = "bear";
    $replacements[1] = "black";
    $replacements[0] = "slow";
    print preg_replace($patterns, $replacements, $string);
    /* Output
        ======
    The bear black slow jumped over the lazy dog.
    */
    /* By ksorting patterns and replacements,
        we should get what we wanted. */
    ksort($patterns);
    ksort($replacements);
    print preg_replace($patterns, $replacements, $string);
    /* Output
        ======
    The slow black bear jumped over the lazy dog.
    */
?>

10. 将 HTML 转换成文本

<?php
    // $document 应包含一个 HTML 文档。
    // 本例将去掉 HTML 标记，# 代码
    // 和空白字符。还会将一些通用的
    // HTML 实体转换成相应的文本。
    $search = array ("&#39;<script[^>]*?>.*?</script>&#39;si", // 去掉 #
                     "&#39;<[\/\!]*?[^<>]*?>&#39;si", // 去掉 HTML 标记
                     "&#39;([\r\n])[\s]+&#39;", // 去掉空白字符
                     "&#39;&(quot|#34);&#39;i", // 替换 HTML 实体
                     "&#39;&(amp|#38);&#39;i",
                     "&#39;&(lt|#60);&#39;i",
                     "&#39;&(gt|#62);&#39;i",
                     "&#39;&(nbsp|#160);&#39;i",
                     "&#39;&(iexcl|#161);&#39;i",
                     "&#39;&(cent|#162);&#39;i",
                     "&#39;&(pound|#163);&#39;i",
                     "&#39;&(copy|#169);&#39;i",
                     "&#39;&#(\d+);&#39;e"); // 作为 PHP 代码运行
    $replace = array ("",
                      "",
                      "\\1",
                      "\"",
                      "&",
                      "<",
                      ">",
                      " ",
                       chr(161),
                       chr(162),
                       chr(163),
                       chr(169),
                      "chr(\\1)");
    $text = preg_replace ($search, $replace, $document);
?>