php 正则表达式 preg_replace-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_1458/article/details/81897588

本文通过几个具体的PHP正则表达式示例介绍了如何进行URL转换、特殊字符转义及文本格式化等操作。首先展示了如何将普通文本中的URL转换为超链接，接着解释了如何在字符串中正确处理HTML特殊字符，最后演示了批量处理字符串数组的方法。

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练习一:


<?php
$txt = "This is a link to http://www.google.com/";
$pattern1 = '/http:\/\/(.*)\//';
$pattern2 = '/http:\/\/(.*)\//e';
$replacement1 = "<a href='$0'>$1</a>";
$replacement2 = 'strtoupper("<a href=\'$0\'>$1</a>")';
echo preg_replace($pattern1, $replacement1, $txt);
//This is a link to <a href='http://www.google.com/'>www.google.com</a>

echo "<br />";
echo preg_replace($pattern2, $replacement2, $txt);
//This is a link to <A HREF='HTTP://WWW.GOOGLE.COM/'>WWW.GOOGLE.COM</A>
?>

练习二:


$txt = "sss <b> &";
$pattern = '/[&<">]/e';
$replacement = array('&' => '&', '<' => '<', '>' => '&gt', '"' => '"');
echo preg_replace($pattern, '$replacement["$0"]', $txt);
//sss <b&gt &

练习三:


$subjects = array("sss <b> &", "<b>aaa</b>");
$patterns = array('/&/', '/</', '/>/', '/"/');
$replacements = array('&', '<', '>', '"');
$rs_array = preg_replace($patterns, $replacements, $subjects);
print_r($rs_array);

/*
Array
(
    [0] => sss <b> &
    [1] => <b>aaa</b>
)
*/

preg_replace_callback函数


<?php
$txt = "vim --- vim -";
$pattern = '/\bvim\b/';
function fn_callback($matches) {
    return "<b>" . $matches[0] . "</b>";
}
$rs = preg_replace_callback($pattern, "fn_callback", $txt);
echo $rs;
//<b>vim</b> --- <b>vim</b> -
?>