在PHP中修剪字符串中的HTML标记

Question

Why is that trim() returns i>abc</i instead of <i>abc</i> when using trim($string, "<br />") on the string below?

$string = "  <br />   <br /> <i>abc</i>  <br /> <br />   </br>";

I wanted to remove all <br /> tags from the beginning and end of the string considering that there might be some whitespaces in between <br> tags.

Any suggestions or workarounds?

Answer 1

The second parameter to trim isn't a string as such, more a list of chars you want to strip from the start and end of the string. So, you're telling to strip all leading and trailing <, >, \, b and r characters.

Could try something like this regex to strip what you want from the front and end of a string...

//trim from start
$str=preg_replace('{^(?:<br />|</br>|\s+)+}', '', $str);
//trim from end
$str=preg_replace('{(?:<br />|</br>|\s+)+$}', '', $str);

Just to break down that first one...

• I've used {} to delimit my regex, just so I don't need to escape the matches on backslashes which I'd have to if I used the 'normal' // delimiter
• ^ anchors the match to the start of the string
• (?: ) is just a group of things we want to look for
• inside the group, we match either <br />, </br> or any whitespace sequence \s+ - you can see each of these patterns is separated by | to indicate each is a possible alternative match
• the group is followed by + to indicate we want to find one or more matches of that group

The second one is similar, but anchored to the end of the string with $