1..4
ok 1 - array
ok 2 - substr
ok 3 - pack
ok 4 - regex
               Rate  arraywise  regexwise   packwise    bitwise substrwise
arraywise    38.9/s         --       -75%       -86%       -98%      -100%
regexwise     153/s       294%         --       -43%       -93%      -100%
packwise      270/s       593%        76%         --       -87%      -100%
bitwise      2077/s      5239%      1255%       671%         --       -99%
substrwise 187563/s    481985%    122274%     69480%      8930%         --