php preg_replace 如何只替换选择器内匹配的 xxx($1)yyy 模式
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preg_replace how to replace only matching xxx($1)yyy pattern inside the selector
提问by PartySoft
I'm trying to use a regular expression to erase only the matching part of an string. I'm using the preg_replacefunction and have tried to delete the matching text by putting parentheses around the matching portion. Example:
我正在尝试使用正则表达式来仅删除字符串的匹配部分。我正在使用该preg_replace函数并尝试通过在匹配部分周围放置括号来删除匹配的文本。例子：
preg_replace('/text1(text2)text3/is','',$html);
This replaces the entire string with '' though. I only want to erase text2, but leave text1 and text3 intact. How can I match and replace just the part of the string that matches?
不过，这会用 '' 替换整个字符串。我只想擦除 text2，但保持 text1 和 text3 不变。如何仅匹配和替换匹配的字符串部分？
回答by mario
There is an alternative to using text1and text3in the match pattern and then putting them back in via the replacement string. You can use assertionslike this:
还有就是要使用替代text1，并text3在匹配模式，然后把它们放回通过替换字符串。您可以使用这样的断言：
preg_replace('/(?<=text1)(text2)(?=text3)/', "", $txt);
This way the regular expression looks just for the presence, but does not take the two strings into account when applying the replacement.
这样，正则表达式只查找是否存在，但在应用替换时不会考虑这两个字符串。
http://www.regular-expressions.info/lookaround.htmlfor more information.
回答by Mansoor Siddiqui
Use backreferences(i.e. brackets) to keep only the parts of the expression that you want to remember. You can recall the contents in the replacement string by using $1, $2, etc.:
使用反向引用（即括号）仅保留您想要记住的表达式部分。您可以通过使用召回替换字符串中的内容$1，$2等：
preg_replace('/(text1)text2(text3)/is','',$html);
回答by aorcsik
Try this:
尝试这个：
$text = preg_replace("'(text1)text2(text3)'is", "", $text);
Hope it works!
希望它有效！
Edit:changed \\1\\2to $1$2which is the recommended way.
编辑：更改\\1\\2为$1$2推荐的方式。
回答by abesto
The simplest way has been mentioned several types. Another idea is lookahead/lookback, they're overkill this time but often quite useful.
最简单的方法已经提到了几种类型。另一个想法是前瞻/回顾，这次它们有点矫枉过正，但通常非常有用。
