Contents

Instructions

This lab has two parts about parsing (reading and interpreting) input files. In the first part, you'll calculate the percentage of area a county takes up in its state and in the second part, you'll scan through a file to find a contact's information.

Part 1: County area

For this part, you will create a C++ program to parse a file with two columns: a place name (e.g., a county within a state) followed by an area in square miles. The program should add a third column to the data in a new file, which is, for each line of data, the percentage of that county's area relative to the total area across all counties. So, for example, for an input file that looks like this:

Barnstable  396
Berkshire   931
Bristol     556
Dukes       104
Essex       498
Fraklin     702
Hampden     618
Hampshire   529
Middlesex   824
Nantucket   48
Norfolk     400
Plymouth    661
Suffolk     58
Worcester   1513

your program should produce an output file that looks like this:

Barnstable  396     0.05
Berkshire   931     0.12
Bristol     556     0.07
Dukes       104     0.01
Essex       498     0.06
Fraklin     702     0.09
Hampden     618     0.08
Hampshire   529     0.07
Middlesex   824     0.11
Nantucket   48      0.01
Norfolk     400     0.05
Plymouth    661     0.08
Suffolk     58      0.01
Worcester   1513    0.19

Write your program in a file called lab10-part1.cpp. Your program should read the name of the input file, the name of the output file, then carry out the computation. It should ensure that the input file exists before trying to read data from it, and if not, ask the user for another filename until one is found that exists. This is fairly simple to test: after opening the file (e.g., inFile.open(filename.c_str());), test if the file is good: inFile.good();. The good() method will return true if the file exists and can be read.

You may assume that the county name will always be a single word (no spaces).

HINTS: You may want to consider reading the file twice, or storing the data you read in the first time in a way that lets you iterate over it again. Also, when you go to run your program, provide an output filename that is different from your input file name, or else you'll overwrite your input file.

Your program should be able to handle any input in the format described earlier. For instance, it should handle processing a file with the following New Jersey county areas:

Atlantic    569
Bergen      234
Burlington  819
Camden      221
Cape-May    267
Cumberland  500
Essex       130
Gloucester  329
Hudson      47
Hunterdon   423
Mercer      228
Middlesex   312
Monmouth    476
Morris      468
Ocean       642
Passaic     192
Salem       365
Somerset    307
Sussex      527
Union       103
Warren      362

Challenge: Formatting can be tricky. See if you can figure out how to get the spacing in the output file to look like the example above, and display the percentage to two decimal places.

Part 2: Contact

Write a C++ program that will prompt a user for a file of contacts and for the last name of a contact to search for. If the file does not exist, the program should report the error "File not found" and ask the user for another filename until one is given that is found. The program should then search the file for that contact's last name. If found, the program should print out the contact's information (phone number, email, etc.) to the console, and if not found, it should print "Contact not found." to the console. The contact file will consist of the following four lines of text per contact:

last name
first name
phone #
email

Each line may consist of spaces (for instance, a last name could be "Van Helsing"), so be sure that your method for reading each piece of information can handle that. Here's an example input file:

De Niro
Robert
(555) 444-3333
bdeniro@hollywood.com
Pachino
Al
(555) 444-3334
al@mafia.com
Hanks
Tom
(777) 555-4444
th@big.com
Streep
Meryl
(333) 555-3232
streep@hotmail.com
Hepburn
Audrie
(492) 492-4924
ahep@movies.com

Try creating your own!

Challenge: Adapt the program so that it asks for the file once, but then keeps asking the user for names until the user indicates they want to stop (using a sentinel value).

Submission

Submit your .cpp files from parts 1 and 2 to here.

(Back to top)