Yes it does:

    (?:     - group, but don't generate back ref
     \.     - a dot
     \d+    - followed by one or more digits
    )?      - and the whole thing is optional
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So \d+(?:\.\d+)? matches a group of digits, optionally followed by a dot and more digits. So, it matches an integer or a float.

If you want to allow things like "20." (no numbers after the dot) you would have it to \d+(?:\.\d*) (asterisk instead of plus sign after the second \d).

--ZZamboni