Thanks - missed that (and I guess I should have searched harder as this is a command problem: apologies). Nice regex though - finally see the point of \G ;) 
$num =~ s/(^[-+]?\d+?(?=(?>(?:\d{3})+)(?!\d))|\G\d{3}(?=\d))/$1,/g;

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Thanks.

In reply to Re^2: Formatting a number by harryf
in thread Formatting a number by harryf

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