Perl Cookbook

Printing Correct Plurals

Problem

You’re printing something like "It took $time hours", but "It took 1 hours" is ungrammatical. You would like to get it right.

Solution

Use printf and a ternary conditional (X ? Y : Z) to alter the noun or verb:

printf "It took %d hour%s\n", $time, $time == 1 ? "" : "s";

printf "%d hour%s %s enough.\n", $time, 
        $time == 1 ? ""   : "s",
        $time == 1 ? "is" : "are";

Or, use the Lingua::EN::Inflect module from CPAN as described in the Discussion.

Discussion

The only reason inane messages like "1 file(s) updated" appear is because their authors are too lazy to bother checking whether the count is 1 or not.

If your noun changes by more than an "-s", you’ll need to change the printf accordingly:

printf "It took %d centur%s", $time, $time == 1 ? "y" : "ies";

This is good for simple cases, but you’ll get tired of writing it. This leads you to write funny functions like this:

sub noun_plural {
    local $_ = shift;
    # order really matters here!
    s/ss$/sses/                             ||
    s/([psc]h)$/${1}es/                     ||
    s/z$/zes/                               ||
    s/ff$/ffs/                              ||
    s/f$/ves/                               ||
    s/ey$/eys/                              ||
    s/y$/ies/                               ||
    s/ix$/ices/                             ||
    s/([sx])$/$1es/                         ||
    s/$/s/                                  ||
                die "can't get here";
    return $_;
}
*verb_singular = \&noun_plural;   # make function alias

As you find more exceptions, your function will become increasingly convoluted. When you need to handle such morphological changes, turn to the flexible solution provided by the Lingua::EN::Inflect module from CPAN.

use Lingua::EN::Inflect qw(PL classical); classical(1); # why isn't this the default? ...