#!/usr/bin/perl
use 5.016;
use warnings;

# 1071410  change ONLY numbers which are (one digit only) 0 

my @arr = qw(20 14 007 0 1203  '' 7900130 43.02 0.03 0.0 ); 
for my $elem(@arr) { 
    if ( $elem=~ /^0{1}$/ ){ 
        say $elem;
        my $elem1 = $elem =~ s/^0{1}$/1/;
        say $elem1;
    }
}
say "above, results from Ln1-14; below: Kenosis' 3: \n";

my @arr3 = qw(20 14 007 0 1203  '' 7900130 43.02 0.03 0.0 ); 
for (@arr3) {
    print "Original \@arr3 element: |$_| becomes (or remains as) ";
    $_ = 1 if $_ == 0;
    say $_;
}

say "\n Kenosis' 1 (boundary version): ";

my @arr1 =  qw(20 14 007 0 1203  '' 7900130 43.02 0.03 0.0 ); 
for (@arr1) { 
    s/\b0\b/1/;
    print "Original \@arr1 element: |$_| becomes (or remains as) ";
    say $_;
}