Task — Find pairs

You are given a string of delimiter pairs and a string to search. Write a script to return two strings, the first with any characters matching the “opening character” set, the second with any matching the “closing character” set.

Examples

Example 1:
Input:
    Delimiter pairs: ""[]()
    Search String: "I like (parens) and the Apple
        ][+" they said.
Output:
    "(["
    ")]"

Example 2:
Input:
    Delimiter pairs: **//<>
    Search String: /* This is a comment (in some 
        languages) */ <could be a tag>
Output:
    /**/<
    /**/>

Analysis

The task description is not entirely clear, though the examples help a bit.

My approach is to make strings of the opening and closing characters and then use:

$openers =~ s|[^\Q$opens\E]||g;
$closers =~ s|[^\Q$closes\E]||g;

to remove those characters from the input string.

I hope that's what was wanted.

Try it 

#!/usr/bin/perl
use strict;
use warnings;
use v5.26;

my ($delimiter_pairs, $search_string, $openers, $closers);

# loop over input values
until (eof(DATA)) {
    $delimiter_pairs = <DATA>;;
    $search_string = <DATA>;
    chop($delimiter_pairs, $search_string);
    do_task();
}

sub do_task {

    my ($openers, $closers, $opens, $closes);

    # copy the search string
    $openers = $closers = $search_string;

    # pick off the delimiters in pairs and make strings of the opening and closing characters
    while ($delimiter_pairs =~ m|(.)(.)|g) {
        $opens .= $1;
        $closes .= $2;
    }

    # remove all but the opening characters from $openers and similarly with $closers
    $openers =~ s|[^\Q$opens\E]||g;
    $closers =~ s|[^\Q$closes\E]||g;

    say qq[\nDelimiter pairs: $delimiter_pairs];
    say qq[Search string: $search_string];
    say qq[Openers: $openers];
    say qq[Closers: $closers];
}

__DATA__
""[]()
"I like (parens) and the Apple ][+" they said.
**//<>
/* This is a comment (in some languages) */ <could be a tag>
{}##^!
    {note 1} #danger# ^switch off power first! #by order#

Output

Delimiter pairs: ""[]()
Search string: "I like (parens) and the Apple ][+" they 
    said.
Openers: "(["
Closers: ")]"

Delimiter pairs: **//<>
Search string: /* This is a comment (in some languages) */
    
Openers: /**/<
Closers: /**/>

Delimiter pairs: {}##^!
Search string: 	{note 1} #danger# ^switch off power first!
    #by order#
Openers: {##^##
Closers: }##!##