负后视正则表达式在 PHP 中不起作用

Question

我用 PHP 编写了一段代码，旨在匹配一个副词（以“ly”结尾的单词），该副词不应匹配任何单词 daily、weekly、monthly、bi-daily、bi-weekly 等。

例如，给定句子Locally meet daily for 3 days, only Locallyshould match。

我使用负向后看确定了 Regex 语法，但 PHP 向我抛出一个错误：

编译失败：lookbehind 断言在偏移处不是固定长度..

这是我在 PHP 中的完整代码：

<?php

$sentence = "Locally meet daily for next 3 days";

// Use preg_match() function to check match 

preg_match('/(\w+ly)(?<!(daily|weekly|monthly))/', $sentence, $matches, PREG_OFFSET_CAPTURE); 

// Display matches result 

print_r($matches); 

我试过负面前瞻，但它并没有给我带来可喜的结果。有人会建议可以做什么吗？谢谢

Answer 1

您可以使用否定前瞻，但它需要在您的匹配组之前。您还需要在正则表达式的开头添加一个断字 ( \b) 断言，以便（例如）正则表达式不匹配ailyin daily，另一个在末尾，这样您就不会ly在中间匹配单词 with 例如newlywed：$sentence = "Locally meet daily newlywed for next 3 days";preg_match_all('/\b(?!(?:daily|weekly|monthly))(\w+ly)\b/', $sentence, $matches, PREG_OFFSET_CAPTURE);&nbsp;print_r($matches);&nbsp;输出：Array(&nbsp; &nbsp; [0] => Array&nbsp; &nbsp; &nbsp; &nbsp; (&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [0] => Array&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [0] => Locally&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [1] => 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; )&nbsp; &nbsp; &nbsp; &nbsp; )&nbsp; &nbsp; [1] => Array&nbsp; &nbsp; &nbsp; &nbsp; (&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [0] => Array&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [0] => Locally&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [1] => 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; )&nbsp; &nbsp; &nbsp; &nbsp; ))3v4l.org 上的演示