In my PHP code I've been using [:space:] and [:print:] for matching space and non-space characters respectively. I however came across one case where preg_match was unable to find a match even though it should have. Replacing [:space:] with \s solved the problem. Due to this I realized all my other uses of [:space:] in the code could fail unexpectedly at some point in the future and so embarked on replacing all of them with \s.
My question is why did [:space:] fail where \s worked? The original regexp was:
'%\[/row\][[:space:]]+<!-- related_products_section -->[[:space:][:print:]]+<!-- end_related_products_section -->%m'
which I changed into:
'%\[/row\][\s]+<!-- related_products_section -->[\s[:print:]]+<!-- end_related_products_section -->%m'
Another question arising is what is the non-posix equivalent of [:print:]?
