How can I convert text to title case? - perl

Question

I have a text file containing a list of titles that I need to change to title case (words should begin with a capital letter except for most articles, conjunctions, and prepositions).
For example, this list of book titles:
barbarians at the gate
hot, flat, and crowded
A DAY LATE AND A DOLLAR SHORT
THE HITCHHIKER'S GUIDE TO THE GALAXY
should be changed to:
Barbarians at the Gate
Hot, Flat, and Crowded
A Day Late and a Dollar Short
The Hitchhiker's Guide to the Galaxy
I wrote the following code:
while(<DATA>)
{
$_=~s/(\s+)([a-z])/$1.uc($2)/eg;
print $_;
}
But it capitalizes the first letter of every word, even words like "at," "the," and "a" in the middle of a title:
Barbarians At The Gate
Hot, Flat, And Crowded
A Day Late And A Dollar Short
The Hitchhiker's Guide To The Galaxy
How can I do this?

Answer 1

Thanks to See also Lingua::EN::Titlecase – Håkon Hægland given the way to get the output.
use Lingua::EN::Titlecase;
my $tc = Lingua::EN::Titlecase->new();
while(<DATA>)
{
my $line = $_;
my $tc = Lingua::EN::Titlecase->new($line);
print $tc;
}

Answer 2

You can also try using this regex: ^(.)(.*?)\b|\b(at|to|that|and|this|the|a|is|was)\b|\b(\w)([\w']*?(?:[^\w'-]|$)) and replace with \U$1\L$2\U$3\L$4. It works my matching the first letter of words that are not articles, capitalizing it, then matching the rest of the word. This seems to work in PHP, I don't know about Perl but it will likely work.
^(.)(.*?)\b matches the first letter of the first word (group 1) and the rest of the word (group 2). This is done to prevent not capitalizing the first word because it's an article.
\b(word|multiple words|...)\b matches any connecting word to prevent capitalizing them.
(\w)([\w']*?(?:[^\w'-]|$)) matches the first letter of a word (group 3) and the rest of the word (group 4). Here I used [^\w'-] instead of \b so hyphens and apostrophes are counted as word characters too. This prevent 's from becoming 'S
The \U in replacement capitalizes the following characters and \L lowers them. If you want you can add more articles or words to the regex to prevent capitalizing them.
UPDATE: I changed the regex so you can include connecting phrases too (multiple words). But that will still make a very long regex...