#!/usr/bin/perl -w
use strict;

my $patient_id;   #patient record for the CSV file
my $nhs;
my $dob;
my $sex;
my $postcode;

my $total_patients=0;
while (<DATA>)
{
   s/^\s*//;  #remove leading space
   s/\s*$//;  #remove trailing space
   
   $patient_id = $1 if m/^Patient ID .*?(\d+)$/;
   $nhs        = $1 if m/^NAD .*?(\d+)$/;
   $dob        = $1 if m/^Date Of Birth .*?([\/\d]+)$/;
   $sex        = $1 if m/^Sex .*?(\w+)$/;
   
   #record ends with postal code -> output to the CSV file
   
   if ( ($postcode )= m/^Postcode .*?(\w+)$/ )
   {
      print "$patient_id,$nhs,$postcode,$dob,$sex\n";  #CSV line
      
      $total_patients++; # this is here instead of with $patient_id
                         # because it is here that we have an 
                         # "official"  patient record
      
      # this starts variables "over again". A runtime warning will
      # happen if for some reason one of these winds up still
      # being undefined when the record is printed to the CSV file
      #
      # note: doing this for $postcode is not necessary, but I
      # treat this variable same as the others because this lessens
      # the chance of a mistake when modifying the program later.
           
      $patient_id = $nhs = $dob = $sex = $postcode = undef;                      
   }   
}   

print "Total Patients: $total_patients\n";

=prints
1234,5678,BH78,01/01/1965,yes
4321,999,XYZ98,10/10/2007,no
Total Patients: 2
=cut

__DATA__
Patient ID 1234
NAD 5678
Date Of Birth : 01/01/1965
Sex  : yes
Postcode  : BH78
Patient ID 4321
NAD 999
Date Of Birth : 10/10/2007
Sex  : no
Postcode  : XYZ98