Data commit

Task/Multi-dimensional-array/Perl/multi-dimensional-array.pl

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+use feature 'say';
+
+# Perl arrays are internally always one-dimensional, but multi-dimension arrays are supported via references.
+# So a two-dimensional array is an arrays-of-arrays, (with 'rows' that are references to arrays), while a
+# three-dimensional array is an array of arrays-of-arrays, and so on. There are no arbitrary limits on the
+# sizes or number of dimensions (i.e. the 'depth' of nesting references).
+
+# To generate a zero-initialized 2x3x4x5 array
+for $i (0..1) {
+  for $j (0..2) {
+    for $k (0..3) {
+      $a[$i][$j][$k][$l] = [(0)x5];
+    }
+  }
+}
+
+# There is no requirement that the overall shape of array be regular, or that contents of
+# the array elements be of the the same type.  Arrays can contain almost any type of values
+@b = (
+     [1, 2, 4, 8, 16, 32],                                                      # numbers
+     [<Mon Tue Wed Thu Fri Sat Sun>],                                           # strings
+     [sub{$_[0]+$_[1]}, sub{$_[0]-$_[1]}, sub{$_[0]*$_[1]}, sub{$_[0]/$_[1]}]   # coderefs
+);
+say $b[0][5];           # prints '32'
+say $b[1][2];           # prints 'Wed'
+say $b[2][0]->(40,2);   # prints '42', sum of 40 and 2
+
+# Pre-allocation is possible, can result in a more efficient memory layout
+# (in general though Perl allows minimal control over memory)
+$#$big = 1_000_000;
+
+# But dimensions do not need to be pre-declared or pre-allocated.
+# Perl will auto-vivify the necessary storage slots on first access.
+$c[2][2] = 42;
+# @c =
+#    [undef]
+#    [undef]
+#    [undef, undef, 42]
+
+# Negative indicies to count backwards from the end of each dimension
+say $c[-1][-1]; # prints '42'
+
+# Elements of an array can be set one-at-a-time or in groups via slices
+my @d = <Mon Tue Ned Sat Fri Thu>;
+push @d, 'Sun';
+$d[2] = 'Wed';
+@d[3..5] = @d[reverse 3..5];
+say "@d"; # prints 'Mon Tue Wed Thu Fri Sat Sun'