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| -rw-r--r-- | perl.html.markdown | 29 |
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 |