"I think substr would be better for you case"

Actually, no. The OP stressed that he is dealing with octets, not characters. unpack could be a reasonable option, but probably not as clear as the regex unless the maintenance programmer is familiar with pack/unpack. The unpack code would (using the OP's sample data) look like:

my $stuff = '000010100101110001010110010010010100111100111111001001000
+1110110';
my $bytes = pack('B64', $stuff);
my ($prefix, $tail) = unpack('a4a*', $bytes);

print ">$prefix<\n>$tail<\n";

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True laziness is hard work

In reply to Re^2: Pattern match not working sometimes by GrandFather
in thread Pattern match not working sometimes by dantheman1210

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