#need data1.txt and data1.JPG

#data1.txt
#line1
#line2

print "----READ WRITE TEXT FILE----\n";
print "Use '+<' file to open in read only mode\n";
open FILE, "+<", "data1.txt" or die "Cannot open file" ;
print "file data - start\n";
while (<FILE>)
{
  print $_;
}
print "\nfile data - end\n\n";

print "Use '+>>' file to open in write and append mode\n";
print "No new file shall be created\n";
open FILE, "+>>", "data1.txt" or die "Cannot open file" ;
print "Adding lines to the file\n";
print FILE "\nline5\n";
print FILE "line6\n";
open FILE, "+<", "data1.txt" or die "Cannot open file" ;
print "file data - start\n";
while (<FILE>)
{
  print $_;
}
print "file data - end\n";
print "Note: New data is appended to old data\n\n";

print "Use '+>' file to open in write and truncate mode\n";
print "New file shall be created if it already exists\n";
open FILE, "+>", "data1.txt" or die "Cannot open file" ;
print "Adding lines to the file\n";
print FILE "line7\n";
print FILE "line8";
open FILE, "+<", "data1.txt" or die "Cannot open file" ;
print "file data - start\n";
while (<FILE>)
{
  print $_;
}
print "\nfile data - end\n";
print "Note: Old data is deleted\n";

close FILE;

print "\n----READ WRITE JPG/BINARY FILE----\n";
my $buffer;
open INPUTFILE, "+<", "data1.JPG" or  die "Cannot open file" ;
open OUTPUTFILE, ">", "dataOut.JPG" or  die "Cannot open file" ;
binmode INPUTFILE;
binmode OUTPUTFILE;
while (read (INPUTFILE, $buffer, 65536))
{
  print OUTPUTFILE $buffer;
}
close(INPUTFILE);
close(OUTPUTFILE);
print "Note: Now try to open written file to verify it got written correctly\n\n";

print "\n----Now use FILEHANDLE module to read and write----\n";
print "\n----Now use FILEHANDLE module to read----\n";
use FileHandle;
$fh = FileHandle->new;
if ($fh->open("< data1.txt"))
{
  print <$fh>;
  $fh->close;
}

print "\n----Now use FILEHANDLE module to write----\n";
$fh = FileHandle->new("> data1.txt");
print $fh "line9\n";
$fh->close;
$fh = FileHandle->new("< data1.txt");
print <$fh>;
$fh->close;

print "\n----Now use FILEHANDLE module to READ WRITE JPG/BINARY FILE----\n";
$fhIn =  FileHandle->new("< data1.JPG");
$fhOut = FileHandle->new("> dataOut1.JPG");
my $buffer;
binmode $fhIn;
binmode $fhOut;
while (read ($fhIn, $buffer, 65536))
{
  print $fhOut $buffer;
}
$fhIn->close;
$fhOut->close;

$ perl readwritefile.pl
----READ WRITE TEXT FILE----
Use '+<' file to open in read only mode
file data - start
line9

file data - end

Use '+>>' file to open in write and append mode
No new file shall be created
Adding lines to the file
file data - start
line9

line5
line6
file data - end
Note: New data is appended to old data

Use '+>' file to open in write and truncate mode
New file shall be created if it already exists
Adding lines to the file
file data - start
line7
line8
file data - end
Note: Old data is deleted

----READ WRITE JPG/BINARY FILE----
Note: Now try to open written file to verify it got written correctly


----Now use FILEHANDLE module to read and write----

----Now use FILEHANDLE module to read----
line7
line8
----Now use FILEHANDLE module to write----
line9

----Now use FILEHANDLE module to READ WRITE JPG/BINARY FILE----

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