On Wed, 5 Oct 2011 23:44:21 -0500 Chris Stinemetz <chrisstinem...@gmail.com> wrote:
> trying to learn smart matching in an exercise. > > Why does this program output "odd" when I input an even number? > A few comments on your code. > Thank you, > > Chris > > #!/usr/bin/perl > > use warnings; > use strict; > > use 5.010; > > say "Checking the number <$ARGV[0]>"; > You're using $ARGV[0] several times (duplicate code) and it's a positional argument: http://perl-begin.org/tutorials/bad-elements/#subroutine-arguments Better unpack it as: my $number = shift(@ARGV); > my $favorite = 62; > > given( $ARGV[0] ) { > when( ! /^\d+$/ ) { say "Not a number!" } > > my @divisors = divisors( $ARGV[0] ); > Returns arrays as references is preferable. Furthermore, I think you can only put when inside given and not arbitrary code, and that "when()" operates on the datum that was given to given(). > when( @divisors ~~ 2 ) { # 2 is in @divisors > say "$_ is even"; > continue; > } > > when( !( @divisors ~~ 2 ) ) { # 2 isn't in @divisors > say "$_ is odd!"; > continue; > } > > when( @divisors ~~ $favorite ) { > say "$_ is divisible by my favorite number"; > continue; > } > > when( $favorite ) { # $_ ~~ $favorite > say "$_ is my favorite number"; > continue; > } > > my @empty; > when( @divisors ~~ @empty ) { say "Number is prime" } > > default { say "$_ is divisible by @divisors" } > } > Your indentation is erratic. > sub divisors { > my $number = shift; > > my @divisors = (); No need for the «= ()» here. An array is initialised as empty by default. > foreach my $divisor ( 2 .. ($ARGV[0]/2 + 1) ) { Do you want to operate on "$number" or on "$ARGV[0]"? > push @divisors, $divisor unless $number % $divisor; > } > I got a "WTF?" moment when I saw this unless construct. I'd write it as: if ($number % $divisor == 0) { push @divisors, $divisor; } Regards, Shlomi Fish > return @divisors; > -- ----------------------------------------------------------------- Shlomi Fish http://www.shlomifish.org/ Stop Using MSIE - http://www.shlomifish.org/no-ie/ I used to be arrogant. Now I’m simply Perfect. — one of Shlomi Fish’s relatives. Please reply to list if it's a mailing list post - http://shlom.in/reply . -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
