#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11138609
use warnings;

my $have = <<END;
# turn * into - within |...| regions
A |simple*example| is |so*simple| to come*up |with
these*days|
END

my $want = $have =~ s{\|[^|]*\|}{ $& =~ tr/*/-/r }ger;

print "$have\n$want";
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Outputs:

# turn * into - within |...| regions
A |simple*example| is |so*simple| to come*up |with
these*days|

# turn * into - within |...| regions
A |simple-example| is |so-simple| to come*up |with
these-days|
[download]