exercism-perl5

commit 162eb3e5be496c92c17899e418140ce7605ded4d
parent a96d9bbbe005722ef20e7d98d00a971b0db4d85b
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Fri, 26 Nov 2021 22:59:05 +0000

add comments to Matrix.pm

Diffstat:
M
matrix/Matrix.pm
 | 
17
++++++++++++++++-

1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/matrix/Matrix.pm b/matrix/Matrix.pm
@@ -6,16 +6,28 @@ our @EXPORT_OK = qw<row column>;
 
 sub define_matrix {
     my @matrix;
+    # shift is just the parameter that was passed to the subroutine
+    # split on the newline
     my @lines = split /\n/, shift;
+    # push into the matrix a reference to an array which represents
+    # each row.  Elements of the array are found by splitting on
+    # blank space
     push @matrix, [split / /] foreach (@lines);
     return @matrix;
 }
 
+# $input is a reference to a hash with two keys:
+# index, which asks for a row or column, and
+# string, which represents the matrix
+
 sub row {
   my ($input) = @_;
   my $index  = $input->{'index'};
   my @matrix = define_matrix($input->{'string'});
-  return \@{$matrix[$index - 1]};
+  # since we are returning a row, $index-1 is the row within @matrix
+  # we need to return.  In this case, we are returning a reference to
+  # an array which contains the element of the row
+  return $matrix[$index - 1];
 }
 
 sub column {
@@ -23,9 +35,12 @@ sub column {
   my $index  = $input->{'index'};
   my @matrix = define_matrix($input->{'string'});
   my @column;
+  # each row of the matrix is represented by an array.  $row is a
+  # reference to that array.  To get the column, we use [$index-1].
   foreach my $row (@matrix) {
       push @column, $row->[$index - 1];
   }
+  # we need to return a reference to the array containing the column
   return \@column;
 }