PHP 中的 preg_replace - NOT 条件的正则表达式
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preg_replace in PHP - regular expression for NOT condition
提问by Ali
I am trying to write a function in PHP using preg_replace where it will replace all those characters which are NOT found in list. Normally we replace where they are found but this one is different.
我正在尝试使用 preg_replace 在 PHP 中编写一个函数，它将替换列表中未找到的所有字符。通常我们会替换找到它们的位置，但这次不同。
For example if I have the string:
例如，如果我有字符串：
$mystring = "ab2c4d";
I can write the following function which will replace all numbers with *:
我可以编写以下函数，用 * 替换所有数字：
preg_replace("/(\d+)/","*",$mystring);
But I want to replace those characters which are neither number nor alphabets from a to z. They could be anything like #$*();~!{}[]|\/.,<>?' e.t.c.
但我想从 a 到 z 替换那些既不是数字也不是字母的字符。它们可以是 #$*();~!{}[]|\/.,<>?' 等等
So anything other than numbers and alphabets should be replaced by something else. How do I do that?
所以除了数字和字母之外的任何东西都应该用别的东西代替。我怎么做？
Thanks
谢谢
回答by Felix Kling
You can use a negated character class(using ^at the beginning of the class):
/[^\da-z]+/i
Update:I mean, you have touse a negated character class and you canuse the one I provided but there are others as well ;)
更新：我的意思是，你必须使用一个否定的字符类，你可以使用我提供的一个，但还有其他的 ;)
回答by Dmitri
Try
尝试
preg_replace("/([^a-zA-Z0-9]+)/","*",$mystring);
回答by mario
You want to use a negated "character class". The syntax for them is [^...]. In your case just [^\w]I think.
您想使用否定的“字符类”。它们的语法是[^...]. 在你的情况下，[^\w]我只是想。
回答by Tim Pietzcker
\Wmatches a non-alpha, non-digit character. The underscore _is included in the list of alphanumerics, so it also won't match here.
\W匹配非字母、非数字字符。下划线_包含在字母数字列表中，因此它在此处也不匹配。
preg_replace("/\W/", "something else", $mystring);
should do if you can live with the underscore not being replaced. If you can't, use
如果您可以接受不被替换的下划线，应该这样做。如果不能，请使用
preg_replace("/[\W_]/", "something else", $mystring);
回答by Spudley
The \d, \wand similar in regex all have negative versions, which are simply the upper-case version of the same letter.
正则表达式中的\d,\w和类似的都有否定版本，它们只是同一个字母的大写版本。
So \wmatches any word character (ie basically alpha-numerics), and therefore \Wmatches anything except a word character, so anything other than an alpha-numeric.
So\w匹配任何单词字符（即基本上是字母数字），因此\W匹配除单词字符以外的任何字符，因此匹配除字母数字字符以外的任何字符。
This sounds like what you're after.
这听起来像你所追求的。
For more info, I recommend regular-expressions.info.
有关更多信息，我推荐正则表达式.info 。
回答by MTK
Since PHP 5.1.0 can use \p{L}(Unicode letters) and \p{N}(Unicode digits) that is unicode equivalent like \dand \wfor latin
自PHP 5.1.0起可以使用\p{L}（Unicode字母）和\p{N}（Unicode的数字）是Unicode的等价喜欢\d和\w拉美
preg_replace("/[^\p{L}\p{N}]/iu", $replacement_string, $original_string);
preg_replace("/[^\p{L}\p{N}]/iu", $replacement_string, $original_string);
/iumodifiers at the end of pattern:
/iu模式末尾的修饰符：
i (PCRE_CASELESS)
i (PCRE_CASELESS)
u (PCRE_UTF8)see more at: https://www.php.net/manual/en/reference.pcre.pattern.modifiers.php
u (PCRE_UTF8)查看更多：https: //www.php.net/manual/en/reference.pcre.pattern.modifiers.php
