The "+" matches "the previous item" one or more times.

In this case, "the previous item" is a digit [0-9].

So, at least ONE digit is required, but more digits, if present, are acceptable and will match.

In your example of a solitary "4", the "+" does NOT match anything beyond that digit.

The subsequent " *" matches zero or more trailing spaces. See "Quantifiers" in perldoc perlre.

             "I'm fairly sure if they took porn off the Internet, there'd only be one website left, and it'd be called 'Bring Back the Porn!'"
        -- Dr. Cox, Scrubs

In reply to Re: Understanding this particular Regex. by NetWallah
in thread Understanding this particular Regex. by tty1x

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