问题描述
我正在尝试做一些 PHP preg.但是如果我想要一个没有东西的字符串，我似乎无法让它匹配.
I'm trying to do some PHP preg. But it seems to i can't get it to match if i want a string without something in it.
示例:
Hello! My name is [b]Peter Jack[/b]
如果找到 Peter Jack 的姓氏，则不会匹配，但如果找到[b]Peter[/b]"，则会匹配.
If Peter Jack is found with his last name, it will NOT match, but if its found "[b]Peter[/b]" it will match.
任何我不太擅长解释的人，如果还有什么需要帮助我解决这个问题的，请发表评论.
Anyone who I'm kinda bad at explaining things, comment if there is anything else you need to help me solve this.
我可以说的另一种方式是，如果我得到一个网站链接，它将匹配并执行 preg_replace 中的内容，但如果该网站的链接以 .png(图像)结尾不会匹配，也不会建立链接.
Another way I can say it about, is, if i got a link to a website, it will match and do the stuff in the preg_replace, but if the link to the website ends with like .png (an image) it will not match and will not make a link.
example.com/image.png
不会匹配，因为它包含 .png
Will not be matched because it contains .png
example.com/image
将被匹配，因为它不包含 .png
Will be matched because it does not contain .png
推荐答案
不清楚您要查找什么.如果只是[b]Peter[/b]，那么你就不需要正则表达式.
It's unclear what you want to find. If it's just [b]Peter[/b], then you don't need a regex.
如果你想找到一个被 BBCode 粗体标签包围的单词"，使用
If you want to find a single "word" surrounded by BBCode bold tags, use
preg_match('%\[b\]\w*\[/b\]%', $subject)
如果您想在 BBCode 粗体标签中查找任何内容，只要它不包含 Jack，请使用
If you want to find anything within BBCode bold tags as long as it doesn't contain Jack, use
preg_match(
'%\[b\] # Match [b]
(?: # Try to match...
(?!Jack) # (unless the word "Jack" occurs there)
. # any character
)*? # any number of times, as few as possible
\[/b\] # Match [/b]%x',
$subject)
这篇关于Regex/Preg:不匹配，如果找到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！