添加括号时 preg_match 失败

发布于 2024-12-02 17:22:45 字数 1080 浏览 2 评论 0原文

以下是我正在使用的正则表达式的简化。在我的开发计算机上，$pattern1 和 $pattern2 返回匹配项，但是在我的生产计算机上，只有 $pattern1 返回匹配项！显然，$pattern1 和 $pattern2 之间的唯一区别是其中一个单词周围有括号。然而，两者都是有效的模式，应该与给定的干草堆匹配（据我所知）。

$pattern1 = '/\<a name="ERROR TEXT"\>\<\/a\>\s*?validated\s*?\<\/span\>\s*?\<\/h1\>/';
$pattern2 = '/\<a name="ERROR TEXT"\>\<\/a\>\s*?(validated)\s*?\<\/span\>\s*?\<\/h1\>/';
$haystack = '- IFCS msg value, BOOKMARKED AS ERROR TEXT -->
          <a name="ERROR TEXT"></a>
             validated</span>
       </h1>

                <!-- START: .formActionHolder -->
                <div class="formActionHolder">';
preg_match($pattern1, $haystack, $matches);
print_r($matches);

以前有人发现过这个问题吗？请注意，这不是正则表达式的全部 - 这是一个简化版本，我已将其确定为问题所在。在我的实际代码中，“validated”的值不是一个常量 - 因此我使用括号来捕获该词的原因。当然，这些模式在括号内还有其他字符，以便我可以在这里捕获可变单词。这只是一个简化的示例，它解决了我在两个看似不错的正则表达式中遇到的问题。

在我的开发机器上，我使用 php5.3.2 和 PCRE 7.8 库，在我的生产机器上，我使用 php5.2.4 和 PCRE 7.4。

原文

the following is a simplification of a regex i am using. on my development machine both $pattern1 and $pattern2 return a match, however on my production machine only $pattern1 returns a match! clearly the only difference between $pattern1 and $pattern2 is that one of them has brackets around a word. however both are valid patterns which should match the given haystack (as far as i know).

$pattern1 = '/\<a name="ERROR TEXT"\>\<\/a\>\s*?validated\s*?\<\/span\>\s*?\<\/h1\>/';
$pattern2 = '/\<a name="ERROR TEXT"\>\<\/a\>\s*?(validated)\s*?\<\/span\>\s*?\<\/h1\>/';
$haystack = '- IFCS msg value, BOOKMARKED AS ERROR TEXT -->
          <a name="ERROR TEXT"></a>
             validated</span>
       </h1>

                <!-- START: .formActionHolder -->
                <div class="formActionHolder">';
preg_match($pattern1, $haystack, $matches);
print_r($matches);

has anyone found this problem before? note that this is not the whole of the regex - this is a simplified version which i have identified as being the problem. in my actual code, the value of 'validated' is not a constant - hence my reason for using brackets to capture the word. of course the patterns have other characters within the parenthesis as well so that i can capture the variable words here. this is just a simplified example which hones in on the problem that i am having with two seemingly fine regexes.

on my development machine i am using php5.3.2 with the pcre 7.8 library and on my production machine i am using php5.2.4 with pcre 7.4.

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瞎闹 2024-12-09 17:22:45

括号用于在 php 正则表达式中进行分组，除非您转义它们以使它们充当字符本身。

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梦在深巷 2024-12-09 17:22:45

您确定 $pattern2 不匹配吗？在我的日食中，它匹配，显示
数组（[0] => 已验证
[1] =>已验证）

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枫以 2024-12-09 17:22:45

我想到了 $pattern2 中的 ?( 组合，所以我删除了 ? 来制作

$pattern = '/\<a name="ERROR TEXT"\>\<\/a\>\s*(validated)\s*?\<\/span\>\s*?\<\/h1\>/';

并且有效！！它非常奇怪 - 可能甚至是一个错误？

所以看起来 ?(validated) 位被解释为条件子模式，而不是使用问号来使 \s* 不

贪婪在我看来这不是正确的行为

啊……它。有点痛苦，因为现在我的 * 会很贪婪，但在这种情况下，正则表达式模式会满足我的要求......

感谢您所有有用的评论！

i had a thought about the ?( combination in $pattern2 so i removed the ? to make

$pattern = '/\<a name="ERROR TEXT"\>\<\/a\>\s*(validated)\s*?\<\/span\>\s*?\<\/h1\>/';

and that works!! its very strange - possibly even a bug?

so it looks like the ?(validated) bit was being interpreted as a conditional subpattern rather than the question mark being used to make the \s* ungreedy

that doesn't look like correct behavior to me.

ah well...its a bit of a pain since now my * will be greedy. the regex pattern does what i want in this instance though...

thanks for all your helpful comments!

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