Match whole words in utf

Question

I want to replace all occurrences of a with 5. Here is the code that works well:

$content=preg_replace("/\ba\b/","5", $content);

unless I have words like zapłać where a is between non standard characters, or zmarła where there is a Unicode (or non-ASCII) letter followed by a at the end of word. Is there any easy way to fix it?

Answer 1

the problem is that the predefined character class \w is ASCII based and that does not change, when the u modifier is used. (See regular-expressions.info, preg is PCRE in the columns)

You can use lookbehind and lookahead to do it:

$content=preg_replace("/(?<!\p{L})a(?!\p{L})/","5",$content);

This will replace "a" if there is not a letter before and not a letter ahead.

\p{L}: any kind of letter from any language.

Answer 2

$content=preg_replace("/\ba\b/u","5",$content);