in reply to sorting dates in YYYYMMDD format
Don’t make this harder than it needs to be. The reason for using a YYYYMMDD format is that it can “just be sorted as-is,” whether numerically or as a string. Breaking it down into three groups, only to concatenate them in the same order, does nothing at all. If you need to isolate the string from a bigger string, a simple pattern looking for 8 consecutive digits will do it.
In Section
Seekers of Perl Wisdom