This incorporates a bit from the others and a bit of my own. :) Normaly I would shove the prompt into a sub of its own and use it as the condition for the while loop, but here i went with the simpler way! I came from C too although I started with ++ so I had streams for input output instead of printf.

use strict;
use warnings;

my @phrases = ();
my $i = 1;
print "Please enter phrase number " . $i++  . " (or 'stop'): ";
while (<STDIN>) {
   chomp;
   last if /^stop$/;   #only if they put just the word stop
   print "Please enter phrase number " . $i++  . " (or 'stop'): ";
   push @phrases, $_;
}

printphrases(@phrases);
sub printphrases {
    my $i = 1;
    print $i++ . ") $_\n" foreach @_;
}

__DATA__
C:\test>perl input.pl
Please enter phrase number 1 (or 'stop'): hello world
Please enter phrase number 2 (or 'stop'): this is fun
Please enter phrase number 3 (or 'stop'): cool
Please enter phrase number 4 (or 'stop'): dude!
Please enter phrase number 5 (or 'stop'): stop
1) hello world
2) this is fun
3) cool
4) dude!
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