Perl Programming/Filehandles

Perl Advanced output Modifiers Reading files Procedural interface By slurping file This method will read the whole file into an array. It will split on the special variable $/ # Create a read-only file handle for foo.txt open (my $fh, '<', 'foo.txt'); # Read the lines into the array @lines my @lines=<$fh>; # Print out the whole array of lines print @lines; By line processing This method will read the file one line at a time. This will keep memory usage down, but the program will have to poll the input stream on each iteration. # Create a read-only file handle for foo.txt open (my $fh, '<', 'foo.txt'); # Iterate over each line, saving the line to the scalar variable $line while (my $line = <$fh>) { # Print out the current line from foo.txt print $line; } Object-oriented interface Using IO::File, you can get a more modern object-oriented interface to a Perl file handle. # Include IO::File that will give you the interface use IO::File; # Create a read-only file handle for foo.txt my $fh = IO::File->new('foo.txt', 'r'); # Iterate over each line, saving the line to the scalar variable $line while (my $line = $fh->getline) { # Print out the current line from foo.txt print $line; } # Include IO::File that will give you the interface use IO::File; # Create a read-only file handle for foo.txt my $fh = IO::File->new('foo.txt', 'r'); my @lines = $fh->getlines; # Print out the current line from foo.txt print @lines; Perl Advanced output Modifiers