如何在正则表达式中使用常量或var的preg_match / preg_match_all？

I have the following pattern:

preg_match( "/^(.*?\/wp-content\/)([^\?]+)(.*)$/", $src, $src_bits );

Now I want to set wp-content to a constant named WP_CONTENT_FOLDERNAME that holds the folder name. How would I do that?

Simply by using PHP:

preg_match( "/^(.*?\/" . WP_CONTENT_FOLDERNAME . "\/)([^\?]+)(.*)$/", $src, $src_bits );