php preg_match_all因未知原因杀死页面 [英] php preg_match_all kills page for unknown reason

问题描述

我正在尝试验证一堆文本并检查其中是否有任何电子邮件...因此我使用以下代码：

I am trying to validate a bunch of text and check if there are any emails in it... so i use the following code:

if (preg_match_all("/^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\\.([a-zA-Z])+([a-zA-Z])+/", $str, $matches)){

}

这将适用于Page1中的TEXT_A

this will work for TEXT_A in Page1

但是当我进入Page2并尝试再次检查TEXT_A时它将杀死带有问题加载页面错误的页面...

but when i go in Page2 and try to check again on TEXT_A it will kill the page with "Problem loading page" error...

如果我删除此检查页面将很好加载...我不知道为什么会这样...

if i remove this check the page will load fine... i dont get why this is happening...

edit：im使用CodeIgniter

edit:im using CodeIgniter

推荐答案

正则表达式中的一个问题，该问题可能导致灾难性的回溯。

I see a problem in your regex that could cause Catastrophic Backtracking.

^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\\.([a-zA-Z])+([a-zA-Z])+
                                       ^^^^^^^^^^^^^^^^^^^^^^

您想在我标记的区域匹配什么？

What do you want to match in the area I marked?

正则表达式如何知道第二组的哪封信应适用？

How should the regex know from which letter on the second group should apply?

如果您可以匹配的字母序列较长，则正则表达式将需要很多步骤来匹配 ==>您遇到了性能问题，正则表达式只是不及时完成！

If you have a longer sequence of letters that can match, the regex will need a lot of steps to match that ==> you have a performance problem, the regex just don't finish in time!

我想说，您可以删除最后一组，而正则表达式将匹配相同的组，但是速度要快得多。

I would say you can just remove the last group and the regex will match the same, but much faster.

^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\\.([a-zA-Z])+

这篇关于php preg_match_all因未知原因杀死页面的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！