perl 5.6.1:
> perldoc -f sprintf
v interpret string as a vector of integers, output as
  numbers separated either by dots, or by an arbitrary
  string received from the argument list when the flag
  is preceded by C<*>
 
The "v" flag is useful for displaying ordinal values of
  characters in arbitrary strings:

      printf "version is v%vd\n", $^V;          # Perl's version
      printf "address is %*vX\n", ":", $addr;   # IPv6 address
      printf "bits are %*vb\n", " ", $bits;     # random bitstring
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  p