my $input_file;
my $line;        
open( $input_file, '<', $ARGV[0] )
        or die "Open file $ARGV[0] failed $!";

while ($line = <$input_file>) {
    chomp $line;
    my @fields = split(/\|/, $line);

#Check if record is a valid record type    
    if ($fields[0] !~ /$record_types/) {
        fatal_error (2, "record contains invalid file type fields[0] - Record: $line");
        exit 0;
    }
#Check if number of fields in record matches the number in the record layout
    
    my $expected_nbr_of_fields_in_record = keys %{$rec_layout_hash{$fields[0]}};
    my $actual_fields_count = @fields;
    
    if ($actual_fields_count != $expected_nbr_of_fields_in_record) {
        fatal_error  (1, "record does not contain correct number of fields - Expected $expected_nbr_of_fields_in_record but record contained $actual_fields_count fields -  $line");
        exit 0;
    }
#Process each field from the input data one field at a time
    for (my $i = 1; $i <= $actual_fields_count; $i++) {
    	    my $j = $i;
    	    $j -= 1;                              #$j is minus 1 because the fields array starts at zero, whilst the actual field number in the record array starts at 1
    
#Determine which sub routine is required to check the data from the record_layout hash    
          my $sub_routine = $rec_layout_hash{$fields[0]}{$i}{"sub_routine"};

#Call sub routine and pass the actual field day and the expected length of the fiel
          my $value1 = $fields[$j];
          my $value2 = $rec_layout_hash{$fields[0]}{$i}{"field_length"};
          
          &{ $sub_routine } ($value1, $value2);
    }
}