A large linked-list database

The file /home/218/million-database.txt contains records for exactly
one million randomly generated people, one person per line. The
individual pieces of information are: social security number, day
of birth, month of birth, year of birth, first name, last name,
secret code, zip code, favourite day of the week, and favourite
beatle. The items are separated by spaces, and no item ever contains
a space. Here is a small selection from some way into the file.

      346671424 25 04 1953 Simba VonRichthofen iPSD1jpE 18617 Monday Ringo
      346672433 02 10 1952 Brent Mozart Bup1v6FX 18907 Wednesday Ringo
      346673675 08 06 1974 Alexandra Lamprey YNbEg0Lt 26118 Monday Ringo
      346674451 17 10 1970 Ezra Osmond 8nenexhH 54979 Thursday George  
      346675987 07 08 1997 Nancy Dornier JxoKZszB 56664 Thursday Ringo
      346676332 12 02 1974 Arthropod Tumor PTGS4Ifb 17828 Sunday John  
      346677449 18 05 1987 Lillian DeMorgan 7vel34Ds 71997 Saturday George
      346678718 25 08 1959 Terence Silverman 0JVurP0u 79743 Saturday John
      346679758 01 04 1999 Ralph Frampton UXsW6mOz 46812 Thursday Ringo
      346680428 29 05 1990 Betty Osborne sVZdggQ6 69709 Thursday George
      346680534 23 07 1964 John Floyd GJJYvF88 75947 Friday Paul  

Define a struct or class to represent a person, and List and Link
classes to store them all in a linked list. Think about good design
requirements.

Your program should read the database file and create a linked list of
all of the people. It should then enter an interactive loop, accepting
and obeying the following commands:

exit
               obvious
find fn ln
               find the person(s) with first name fn and last name ln
               and print all of their details
zip z
               print the names only of everyone with zip code z
oldest
               find the oldest person in the database and print all of
               their details
count b
               print the number of people whose favourite beatle is b
sublist a b
               (a and b are both numbers) print all the details of
               everyone from position a (zero meaning the first person
               in the list and 999999 meaning the last) to position b
               inclusive
reverse
               reverse the order of the people. They are currently
               arranged in order of increasing social security number,
               reverse should leave them in order of decreasing social
               security number. A second reverse would restore the
               original order
remove s
               remove the person whose social security number is s
unyear y
               remove all the people who were born in year y
save f
               save the contents of the database in a file named f.
               It should have exactly the same format as the original
               file.

Make a session neat and tidy, no unnecessary prompts, commands typed on
single lines, uncluttered output.

It should only take a second or two to read the file, but writing the
new file could take substantially longer so be patient. But not too
patient, your program might be stuck in an infinite loop. Perhaps make
the save command print a dot after every 20,000 people or something like
that. Remove the dot prnting before turning it in, it is only to help
you be sure your program is working.

Proper testing is, as always, a requirement.

If something does go wrong, it is easier to debug if the file is much
smaller. Rabbit has a utility called lines, which can be used to extract
a number of lines from anywhere in a text file:

  To extract the first 20 lines
      lines 1 20 /home/218/database-million.txt
    or
      lines 1 +20 /home/218/database-million.txt
  To extract the middle 20 lines
      lines 499990 500009 /home/218/database-million.txt
    or
      lines 499990 +20 /home/218/database-million.txt
  To extract the last 20 lines
      lines -20 +20 /home/218/database-million.txt
    or
      lines -20 -1 /home/218/database-million.txt

In case it isn't clear, the two numbres are line numbers, the first
line in a file is line 1. A negative number counts backwards from the
end of the file, the last line in a file is line -1. If the second
number begins with a + sign, it is the number of lines wanted.

So by redirecting the output as in

      lines 499990 500009 /home/218/database-million.txt > sample.txt

you create your own file called sample.txt containing just the middle
20 lines from the giant file.