RoadRoute1.5 - A start at a "trip planner"
                Jim Butterfield .. April 1990

Ya got this file of cities (Called "Cities") showing a lot of places in
North America, but not all of 'em.  (Add the ones you want, using your
favorite editor).

Ya got this file of road segments (Called "Routes") showing roads
connecting the cities; most of the interstates, and quite a few
others that seem handy.  (Add your own road segments if they are
not already there).  The segments show mileage and driving time,
this last worked out within the conservative 55mph framework.
If you're a speed demon, try not to change the numbers .. just
divide the time by two or whatever your thing is.  And when you
add routes, keep 'em consistent, so that back roads don't start
to look like throughways.

And then, ya got this program (compiled from Lattice C) which sez
how ya might get from one place to another.  The first version in
Basic sorted out the logic flow but wasn't too quick; you'll like
the speed of this C version much better.


So .. you're interested in places not given in the original files?
Say, you live in Erie, PA, and love to visit your auntie in
Lake Havasu City, Arizona?  So you wanta add these?  No problem.

Step 1:  Add the city names to the Cities file using your favorite
editor.  For someplace like Lake Havasu, you might like to slip
in a few nearby cities, such as Needles and Kingman.

Step 2:  Start up your editor on the Routes file.  Don't worry
about those numbers ahead of the city names .. the computer will
know what to do if the numbers are not there.  Give road links
hooking up to nearby points in all directions.  For Erie, this
would be:  Buffalo to the east, Cleveland to the West, and
Youngstown to the South (three new lines).
   For Lake Havasu, you'd first want to hook up Kingman to
Flagstaff, Las Vegas, and Needles; then Needles to Barstow.
Finally, you can put in the details for Lake Havasu to Kingman
and Needles; a total of six new lines.
   Be sure to give for each line: two city names, distance,
(sedate) driving time, and highway designation.



   No need to give state designation on the Routes file unless
you have a city name that matches that of a city in another
state.  More on that in a moment.
   Some users have loaded up the data base with their local
towns.  That's fine, but try to keep the information consistent.
If my data sez Los Angeles to San Francisco is 7 hours, try not
to supplement the list with LA-Bakersfield 30 minutes; Bksfield
-SF 4 hours.  You might drive that way, but the data base would
start to have inconsistencies.  See program RoadScan which helps
to watch for this kind of thing.
  If you want to add, say, Jacksonville, North Carolina, you'll
need to think about the name:  there's also a Jacksonville,
Florida, in the system.  No worry:  pop it in the Cities file
anyway, and the computer will know what to do.  You can designate
which Jacksonville you want by using a slash followed by the state
name, e.g., Jacksonville/North Carolina.  If you don't do this,
the computer will complain, showing you the Jacksonville entry in 
the Routes file.  Athough it's finicky about file contents, it
tries to show you the problem areas.


  If programming stuff interests you:  this should be a simple
program.  But "user friendliness", in the form of dialog on
poorly identified places, takes up a little space.  A more
important area is speed:  with hundreds of cities and many
hundreds of routes in the system, linear searches become slow
and painful.
           As a result, you'll find several examples of "linked
lists" here, one of them partly prioritized.  These help find
duplicate city names; greatly speed the search for which routes
apply to a given city; and direct the computer as to which
city point should be searched next.
             The program has no limit on the number of cities
or routes that may be used; if your data base gets big you'll
notice a hesitation when the program starts up.  To help with
huge menu lists, which scrolled off the screen in version 1.0,
the menu now comes in chunks of 15 items.  If you miss the
desired city, you can roll the whole list again.
            As I note with amazement that huge data bases are
being built, I've expanded the max itinerary size to 100 lines.


   Feel free to play with this.  If you want to rip out the
existing map, and build a highly detailed map of your area,
be my guest.  (Street maps, I suspect, wouldn't work too well
because one-way streets are not allowed for here).
   Building the files substantially bigger will cost you
run time.  I agonized as to what should be left in and what
taken out (Sorry if your city is not there .. but you can
add it easily enough).
   My data base is built from comparing a variety of sources:
various maps, AAA data, and others.  Class of road, number of
lanes, whether flat or hilly country; all are factored in.
The information allows for "pit stops" - meals, gas, coffee -
so that average speeds might seem lower than you would expect.  
Hey - but you know your own countryside better than I possibly
could - cut it to your own style.
   A map?  It's quite possible, if you add "north/south,
east/west" coordinates to the Cities file.  I did not do it
here because it would be harder for you to add new cities...
you'd have to know (and type in) the coordinates for each.