File input / output

Opening a filehandle

In order to use a filehandle other than STDIN, STDOUT and STDERR, the filehandle needs to be opened.

The open function opens a file or device and associates it with a filehandle.

It returns 1 upon success and undef otherwise.

Examples

# open a filehandle for reading:
 
open (SOURCE_FILE, "filename");   # or
open (SOURCE_FILE, "<filename");


# open a filehandle for writing:

open (RESULT_FILE, ">filename");


# open a filehandle for appending:

open (LOGFILE, ">>filename";


# open a filehandle for both reading and writing:

open (IN_OUT_FILE, "+>filename");   # or
open (IN_OUT_FILE, "+<filename");


# SOURCE_FILE, RESULT_FILE, LOGFILE and IN_OUT_FILE are examples
  of filehandle names.

Note:

You may write a variable name instead of "filename". Examples: 
my $in_file = "filename1";
open (SOURCE_FILE, "$in_file");

my $out_file = "filename2";
open (RESULT_FILE, ">$out_file");
Next.