use warnings;
use strict;


my $string = 'Three, Four, One, Two, xFive9, six, Seven';

my $number = qr{ \b [[:upper:]] [[:lower:]]+ \b }xms;

print qq{string is now '$string' \n};

my $ordinal = 0;

$string =~ s{ ($number) }
            { ask_replace(++$ordinal, $-[1], $1) }xmsge;

print qq{new string is '$string' \n};
print qq{done! \n};


sub ask_replace {

    my ($ordinal,
        $offset,
        $string,
        ) = @_;

    my $yes = qr{ (?i) y (?: e (?: s)? )?  }xmso;
    my $ok  = qr{ (?i) o (?:          k)?  }xmso;
    my $accept = qr{ \A (?: $yes | $ok) \Z }xmso;

    print qq{sub-string $ordinal at offset $offset is '$string' \n};

    print qq{is this correct? };
    my $answer = <stdin>;
    return $string if $answer =~ $accept;

    print qq{no: enter new string: };
    chomp(my $replace = <stdin>);
    return $replace;

    }