如何删除PHP中的前导和尾随非字母数字字符？

问题描述：

I'm looking to "trim" non-alphanumerics from a string, similar to how trim() works with whitespace.

Help me convert #str|ng# to str|ng.

I can remove trailing non-alphanumerics with:

$string = preg_replace('/\W+$/', '', $string); // converts `#str|ng#` to `#str|ng`

And leading with:

$string = preg_replace('/^\W+/', '', $string); // converts `#str|ng#` to `str|ng#`

But how can I accomplish both at the same time?

我希望从字符串中“修剪”非字母数字，类似于trim（） code>适用于空白。 p>

帮助我将 #str | ng＃ code>转换为 str | ng code>。 p>

我可以删除尾随的非字母数字： p>


  $ string = preg_replace（'/ \ W + $ /'，''，$ string）;  //将`#str | ng #`转换为`#str | ng` 
  code>  pre> 
 
 并以： p> 
 
 
  $ string = preg_replace（'/ ^ \ W + /'，''，$ string）;  //将`#str | ng #`转换为`str | ng＃`
  code>  pre> 
 
 但是如何同时完成两者？ p> \  n  div>

答

Try using a pattern like this:

$string = preg_replace('/^\W+|\W+$/', '', $string);

This will replace any non-word characters (note this doesn't include underscores) which appear either at the beginning or end of the string. The | is an alternation, which will match any string which matches either the pattern on the left or the pattern on the right.

If you also need to remove underscores, use a character class like this:

$string = preg_replace('/^[\W_]+|[\W_]+$/', '', $string);

答

You don't need regex, use trim() and specify what to trim (it trims whitespace by default):

$string = trim($string, "#");

Docs: http://php.net/trim

如何删除PHP中的前导和尾随非字母数字字符？

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