Matching a group that may or may not exist

Question

My regex needs to parse an address which looks like this:

BLOOKKOKATU 20 A 773 00810 HELSINKI SUOMI
-------------------- ----- -------- -----
          1                 


        

Answer 1

This will match your input more tightly and each of your groups is in its own regex group:

(\w+\s\d+\s\w\s\d+)\s(\d+)\s(\w+)\s(\w*)

or if space is OK instead of "whitespace":

(\w+ \d+ \w \d+) (\d+) (\w+) (\w*)

• Group 1: BLOOKKOKATU 20 A 773
• Group 2: 00810
• Group 3: HELSINKI
• Group 4: SUOMI (optional - doesn't have to match)