Re: string substitution

use v5.12;
use warnings;
# https://perlmonks.org/?node_id=11141581

my $in = "anXwxdXdzd";
my $pi = "1415926535";

my @in = split //, $in;
my @pi = split //, $pi;

my $re = join "",
  map {$in[$_] eq "X" ? $pi[$_] : '.' }
  0..9;

$re = "/bin/grep $re /path/to/some/file";

say $re;
[download]

OUTPUT:

/bin/grep ..1...6... /path/to/some/file
[download]

edit

FWIW: Perl can apply mask operations with & , ^ and | , but this would also first require translating X to chr(255) and else to chr(0). see tr and s for that approach.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery}

updates

code now closer to OP's input data

Comment on Re: string substitution Select or Download Code

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Re^2: string substitution by LanX (Saint) on Feb 23, 2022 at 12:41 UTC
> FWIW: Perl can apply mask operations with & , ^ and \| , but this would also first require translating X to chr(255) and else to chr(0). see tr and s for that approach. (used uppercase X for demo only, switching to lowercase works too) `use v5.12; use warnings; # https://perlmonks.org/?node_id=11141581 my $in = "anXwxdXdzd"; my $pi = "1415926535"; my $mask = $in =~ tr/Xa-z/\xff\x00/r; my $re = $pi & $mask; $re=~ tr/\x00/./; $re = "/bin/grep $re /path/to/some/file"; say $re;` [download] OUTPUT: `/bin/grep ..1...6... /path/to/some/file` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re^2: string substitution by Anonymous Monk on Feb 23, 2022 at 12:44 UTC
That worked perfectly. Thank you. I have a twist to add, though. After creating the initial regexp, I want to now check for the letter 'q' in the input string. For each 'q' found, I want to append (for example, with a 'q' in the fourth character of the input line) to the regexp: `' \| grep -v ...5......'` [download] So now, instead of a positive match, I want to check for a negative match (and if I understand regexes, I would need to add that string for each 'q' found in the input line).	[reply] [d/l]
Re^3: string substitution by LanX (Saint) on Feb 23, 2022 at 12:52 UTC
You should at least provide valid data in the sense of an SSCCE, your description is cryptic. Anyway, ISTM you want a character class `[^5]` in the regex to match anything but 5. Please expand the code provided to your needs, and show us what you tried. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l]