#!/usr/bin/perl
use strict;
use warnings;

my $outputfile ="Test_PDB_ID_list.txt";
my $four_char_PDB_ID='';
open (PDB_IDs,">", "$outputfile");
my $PDB_ID= '';

my $dir_to_process= '';
print "What is the directory to process?";

$dir_to_process = <STDIN>;
#$dir_to_process = "Targets-IonChannel";-if I used this #line it would work
#open the folder
unless (opendir(DH, $dir_to_process)){
	print "Cannot open folder $dir_to_process!\n";
	
}
print "$dir_to_process\n";
foreach $PDB_ID (readdir DH){
	$four_char_PDB_ID =substr($PDB_ID,0,4);
	print PDB_IDs "$four_char_PDB_ID\n";
	print "$four_char_PDB_ID \n";
	
	
};

exit;