Description
This week’s assignment will have you write programs that introduce you to loops and functions. Feel
free to work in pairs and ask for help early.
Using the Terminal command line, create a folder (using the mkdir command) called lab03 and cd
into that folder. I have added an example of what should happen when the program is run to the end of
this document. Your source code file must have a preamble at the top (see the programming rules and
guidelines document in Blackboard for more on the preamble).
a. (lab03a.cpp) Write a program that has a hard-coded integer valued from 1 to 5 (just pick a value –
for example: int ans = 3;) and asks the user to guess it. If they get it wrong, the program should
ask them again and keep asking until they guess correctly. You should use a while or do-while
loop for this. Don’t overthink this one.
b. (lab03b.cpp) Write a program that outputs all of the prime numbers between 3 and 100. A prime
number is a number that can only be evenly divided by one and itself (i.e., 3, 5, 7, 11, 13, 17, etc…).
Solve this problem by using a doubly-nested loop. The outer loop will iterate from 3 to 100 and the inner
loop will check to see whether the counter value for the outer loop is prime. One way to decide whether
a number n is prime is to loop from 2 to n-1; if any of these numbers evenly divides n, then n cannot
be prime. If none of the values from 2 to n-1 evenly divide n, then n must be prime.
c. (lab03c.cpp) Rewrite the program from (b) above, but this time create and use a function called
isPrime. The function should take an integer as a parameter and return a Boolean true or false. In
your main(), in the body of the loop from 3 to 100, you’ll call this new function to determine if the
number is prime and decide to output based on the result.
d. (lab03d.cpp) Write a program that outputs the sum of the digits for each number from 0 to 200.
You’ll need to write and use a function called sumOfDigits that takes an integer as a parameter and
returns the sum of its digits (also an integer). To calculate the sum, use the division and modulus
operators to extract the digits one at a time. For example, if the number is 123, observe that (123 %
10) is 3 and (123 / 10) is 12. You will need to use a loop for the extraction of the digits.
Submitting your work
Make sure you are in your lab03 folder (use the pwd command) with your four source code files (use
the ls command) and then run the following to create a zip archive of them:
$ mkdir lastname_firstname_lab03
$ cp lab03a.cpp lastname_firstname_lab03/lab03a.cpp
$ cp lab03b.cpp lastname_firstname_lab03/lab03b.cpp
CSCI 136 Supervised Programming Lab
Lab Assignment #3
Fall 2014 Page 2
$ cp lab03c.cpp lastname_firstname_lab03/lab03c.cpp
$ cp lab03d.cpp lastname_firstname_lab03/lab03d.cpp
$ zip –r lastname_firstname_lab03.zip lastname_firstname_lab03/
You’ll need to change lastname and firstname to your actual last and first names in the steps
above. Once you have your zipfile, you can use that file as your submission for the assignment in
Blackboard.
If you are working in pairs, then you should have both of your names included as comments in the
source code file’s preamble (see the programming rules and guidelines document in Blackboard for
more on the preamble). Also, write both your names to the notes section in the submission form when
submitting to Blackboard.
Sample output
$ ./lab03a
Guess the number I am thinking of (between 1 and 5): 2
No, that is not correct. Guess again: 3
You got it right!
Output is straightforward for parts b, c and d and thus has been omitted.
