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-rw-r--r--perl.html.markdown29
1 files changed, 29 insertions, 0 deletions
diff --git a/perl.html.markdown b/perl.html.markdown
index f03e7244..18339dde 100644
--- a/perl.html.markdown
+++ b/perl.html.markdown
@@ -104,6 +104,35 @@ $a =~ s/foo/bar/; # replaces foo with bar in $a
$a =~ s/foo/bar/g; # replaces ALL INSTANCES of foo with bar in $a
+#### Files and I/O
+
+# You can open a file for input or output using the "open()" function.
+
+open(my $in, "<", "input.txt") or die "Can't open input.txt: $!";
+open(my $out, ">", "output.txt") or die "Can't open output.txt: $!";
+open(my $log, ">>", "my.log") or die "Can't open my.log: $!";
+
+# You can read from an open filehandle using the "<>" operator. In scalar context it reads a single line from
+# the filehandle, and in list context it reads the whole file in, assigning each line to an element of the list:
+
+my $line = <$in>;
+my @lines = <$in>;
+
+#### Writing subroutines
+
+# Writing subroutines is easy:
+
+sub logger {
+ my $logmessage = shift;
+ open my $logfile, ">>", "my.log" or die "Could not open my.log: $!";
+ print $logfile $logmessage;
+}
+
+# Now we can use the subroutine just as any other built-in function:
+
+logger("We have a logger subroutine!");
+
+
```
#### Using Perl modules