Merge remote-tracking branch 'upstream/master'

1 files changed, 27 insertions, 0 deletions

diff --git a/perl.html.markdown b/perl.html.markdown
index 3cbd2801..a29fdf1f 100644
--- a/perl.html.markdown
+++ b/perl.html.markdown
@@ -51,6 +51,13 @@ my @mixed   = ("camel", 42, 1.23);
 # indicate one value will be returned.
 my $second = $animals[1];
 
+# The size of an array is retrieved by accessing the array in a scalar
+# context, such as assigning it to a scalar variable or using the
+# "scalar" operator.
+
+my $num_animals = @animals;
+print "Number of numbers: ", scalar(@numbers), "\n";
+
 ## Hashes
 #   A hash represents a set of key/value pairs:
 
@@ -67,6 +74,11 @@ my %fruit_color = (
 # Hash elements are accessed using curly braces, again with the $ sigil.
 my $color = $fruit_color{apple};
 
+# All of the keys or values that exist in a hash can be accessed using
+# the "keys" and "values" functions.
+my @fruits = keys %fruit_color;
+my @colors = values %fruit_color;
+
 # Scalars, arrays and hashes are documented more fully in perldata.
 # (perldoc perldata).
 
@@ -144,6 +156,12 @@ for (@elements) {
   print;
 }
 
+# iterating through a hash (for and foreach are equivalent)
+
+foreach my $key (keys %hash) {
+  print $key, ': ', $hash{$key}, "\n";
+}
+
 # the Perlish post-condition way again
 print for @elements;
 
@@ -170,8 +188,11 @@ $x =~ s/foo/bar/g;        # replaces ALL INSTANCES of foo with bar in $x
 
 # You can open a file for input or output using the "open()" function.
 
+# For reading:
 open(my $in,  "<",  "input.txt")  or die "Can't open input.txt: $!";
+# For writing (clears file if it exists):
 open(my $out, ">",  "output.txt") or die "Can't open output.txt: $!";
+# For writing (appends to end of file):
 open(my $log, ">>", "my.log")     or die "Can't open my.log: $!";
 
 # You can read from an open filehandle using the "<>" operator.  In
@@ -182,6 +203,12 @@ open(my $log, ">>", "my.log")     or die "Can't open my.log: $!";
 my $line  = <$in>;
 my @lines = <$in>;
 
+# You can write to an open filehandle using the standard "print"
+# function.
+
+print $out @lines;
+print $log $msg, "\n";
+
 #### Writing subroutines
 
 # Writing subroutines is easy: