open my $fh, '<', 'C:\ppp.txt', or die "Could not open file $!";
    while (my $line = <$fh>) 
	{   foreach my $str ($line) 
		{
		  	if (index($line, $address) != -1) 
			{
			  $counter++;
			  $flag='1';
			} 
		}		
	}


##</code><code>##

 open my $fh, '<', 'C:\ppp.txt', or die "Could not open file $!";
if ($fh contains an empty file)
{
 // then add this the $address in the ppp.txt's first line
}