Read specific text patterns in perl [closed] - perl

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I want to read from a text file only specific text, for example:
FileExample:
1111111/first/second/third/fourth.c11111111...etc...
1111111/afirst/asecond/athird/afourth.c11111111...etc...etc
I would like to read the whole file except the part of the file from the 3rd "1" from the first "/" until the ".c" after the 4th "/" to make myself more clear I will bold the text I want my program to read and leave unbolded the part of the text I don't want my program to read.
1111111/first/second/third/fourth.c11111111...etc...etc
1111111/afirst/asecond/athird/afourth.c11111111...etc...etc
after I do all the operations I want with the bolded text,I want to write it in another file the unbolded text unmodified and the bolded text with the modifications made after the operations,and placed in the original file order.
open my $fh1, '<', 'hex.txt';
open my $fh2, '<', 'hex2.txt';
until ( eof $fh1 or eof $fh2 ) {
my #l1 = map hex,unpack '(a2)*', <$fh1>;
my #l2 = map hex,unpack '(a2)*', <$fh2>;
my $n = #l2 > #l1 ? #l2 : #l1;
my #sum = map {
$l1[$_] + $l2[$_];
} 0 .. $n-1;
#sum = map { sprintf '%X', $_ } #sum;
open my $out, '>', 'sum.txt';
print { $out } #sum, "\n";
}
I want to sum the hex values from the file hex to the sum values from file hex2,both files have the same construction type, both have text and hex values in the same location and have the exact same length.i just need to understand how to tell him to read from location1 to location2.
Convert file to hex:
{
my $input = do {
open my $in, '<', $ARGV[0];
local $/;
<$in>
};
open my $out, '>', 'hex.txt';
print $out unpack 'H*', $input;
}

Answer 1

Your precise criteria aren't clear. Are those digits always ones? It's a mistake to show such a very simple example when you're hoping for help. But I suggest you use split
Something like this perhaps?
use strict;
use warnings;
use feature 'say';
my $data = do {
local $/;
<DATA>;
};
$data =~ tr/\n//d;
say for split qr{\d\d\d(?:/\w+)+/\w+\.c}, $data;
__DATA__
1111111/first/second/third/fourth.c11111111...etc...
1111111/afirst/asecond/athird/afourth.c11111111...etc...etc
output
1111
11111111...etc...1111
11111111...etc...etc

Answer 2

I changed the input to be able to recognize what 1's it matches:
abcd111/first/second/third/fourth.cX1111111...etc...
abcd111/afirst/asecond/athird/afourth.cX1111111...etc...etc
This seems to produce the output you want
perl -pe 's=([^/]+).../.*\.c=$1='
[^/] is a character class, it matches anything that's not a slash;
+ means it must be present one or more times
putting it into parentheses makes it a "capture group", i.e. Perl will remember what matched that part.
.../ matches any three character followed by a slash.
.* matches anything.
\.c matches a dot followed by a c.
the whole matching part (abcd in the sample input, up to the c before X) is substituted (hence the starting s) with $1, i.e. the contents of the first capture group, i.e. the abcd in the sample input.