CODEWITHSUNDEEP
perl
Maverick
Maverick

Reputation: 587

Replace binary form 0->1 and 1->0 value - perl

In my script i am dealing with binary value and i need to replace 0->1 and 1->0 at one place.

example : input digit = 10101001 output digit = 01010110

I tried $string =~ s/1/0/; and reverse function but that is getting fail to give me correct out put.

can some one help me out.

Upvotes: 4

Views: 632

Answers (3)

zb226
zb226

Reputation: 10500

You could also go mathy on this and use the bitwise XOR operator ^...

my $input  = '10101001';
my $binval = oct( '0b'.$input );
my $result = $binval ^ 0b11111111;
printf "%08b\n", $result;

...which will also give you 01010110.

This of course has the downside of being dependent on the length of the bit input string. The given solution only works for 8-bit values. It wouldn't be hard to generalize for any number of bits, though.

To incorporate Lưu Vĩnh Phúc's comment - you can also use the bitwise NOT operator ~. Again, the implementation is dependent on the number of bits as you need to truncate the result:

my $input  = '10101001';
my $binval = oct( '0b'.$input );
print substr( sprintf ( '%b', ~$binval ), -8 )."\n";

Upvotes: 2

paxdiablo
paxdiablo

Reputation: 881663

If your input string has only those two possibilities 0 and 1, then you can use substitution in a multi-stage approach:

$str =~ s/1/x/g;  # all 1's to x
$str =~ s/0/1/g;  # all 0's to 1
$str =~ s/x/0/g;  # all x's to 0

This is not a bad option for languages that only provide substitutions, but Perl also has an atomic translation feature:

$str =~ tr/01/10/;

which will work just as well (better, really, since it's less code and probably less passes over the data).

Upvotes: 5

Miller
Miller

Reputation: 35208

Use tr:

my $str = '10101001';

$s =~ tr/01/10/;

print "$s\n";

Outputs:

01010110

Upvotes: 10

Related Questions