preg_replace - 如何转义“[”
我写了这段代码：
<?
$text='how are you [b] today [/b]';
$patterns = array();
$patterns[0] = '/\[b/';
$patterns[1] = '/\b]/';
$replacements = array();
$replacements[1] = 'b]aaa<>';
$replacements[0] = '<>aaa[b';
ksort($patterns);
ksort($replacements);
echo preg_replace($patterns, $replacements, $text);
echo "_";
echo $text;
echo "_";
echo "END";
?>
输出显示：
how are you <>aaa[bb]aaa<> today [/b]aaa<>______how are you [b] today [/b]______END
但输出应该是：
how are you <>aaa[b] today [/b]aaa<>______how are you [b] today [/b]______END
我做错了什么？请帮忙。谢谢
I wrote this code:
<?
$text='how are you [b] today [/b]';
$patterns = array();
$patterns[0] = '/\[b/';
$patterns[1] = '/\b]/';
$replacements = array();
$replacements[1] = 'b]aaa<>';
$replacements[0] = '<>aaa[b';
ksort($patterns);
ksort($replacements);
echo preg_replace($patterns, $replacements, $text);
echo "_";
echo $text;
echo "_";
echo "END";
?>
the output shows:
how are you <>aaa[bb]aaa<> today [/b]aaa<>______how are you [b] today [/b]______END
but the output should be:
how are you <>aaa[b] today [/b]aaa<>______how are you [b] today [/b]______END
what did I do wrong? Please help. Thank you
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评论（2）
您需要对括号进行双重转义：
PHP 在解析字符串时将“消耗”单个反斜杠，只留下一个空的
[，正则表达式引擎将其视为一个字符类。通过双重转义，\\将被 PHP 视为转义，留下单个\，这将被正则表达式引擎视为转义。You need to double-escape the brackets:
A single backslash will be "consumed" by PHP when it parses the string, leaving just a bare
[, which will be seen by the regex engine as the beginning of a character class. By double-escaping, the\\will be seen by PHP as an escape, leaving a single\, which will be seen by the regex engine as an escape.您的问题与转义
[无关。您的问题是您希望 $patterns[1] 仅匹配“/b]”，但这不是您在正则表达式中编写的内容。请尝试使用
'/\/b]/'，或使用备用分隔符（例如'!/b]!'）以避免牙签倾斜综合症。Your problem has nothing to do with escaping
[. Your problem is that you want$patterns[1]to only match "/b]" but that's not what you wrote in your regular expression.Try
'/\/b]/'instead, or use alternate delimiters (e.g.'!/b]!') to avoid leaning-toothpick syndrome.