Pad numerical values in filename with three digit value using sed

Question

I am passing a filename into my bash script and cleaning the name using sed. A few sample files would be:

Test 01.txt
Test v2 01.txt

I would

Answer 1

Instead of

sed -r -e 's/\d+/sprintf("%03d",$&)/e'

use

perl -pe 's/\d+/sprintf("%03d",$&)/ge'