Two notes about "capitalizing all the words on one line":

Here'S An Example Which Isn'T Proper Form, But \B Wouldn'T'Ve Prevented

Also, if you're trying to perform capitalization for captions or titles, please remember that the English rules are more complex than just capitalizing every word. These vary between different prominent style guides, but this is the basic definition:

First and Last words are always capitalized. Other words are NOT capitalized if they're not "important." A good guide for non-important words are articles, conjunctions and prepositions.

This code is something I use on my own site. It's not particularly efficient or clever or even completely rigorous, but it makes most titles look right.

sub titlecase
{
    my @P = qw(a an the and or nor
           of with under over from for behind on in beside at to withi
+n
           de del la las los);
    my $name = shift;
    my @words = split /[._ ]/, $name;
    my $particles = join('|', @P);
    foreach (@words) { $_ = ucfirst($_) if not /^($particles)$/i }
    $words[0] = ucfirst($words[0]);
    $words[-1] = ucfirst($words[-1]);
    return join(' ', @words);
}
[download]

• All Quiet on the Western Front
• Of Mice and Men
• For Whom the Bell Tolls
• Histoire de St. Louis, Roi de France
• Crossing Over

Of course, it leads you back to your original question: what is a word? My code would not handle 'Tis properly, nor parentheses.