CS16: Programming Assignment 05

Introduction

The assignment for this week will utilize concepts of void functions and command line arguments. This assignment is due on Friday, October 28th at noon (12:00 pm)

Step 1: Getting Ready

Open a terminal window and log into the correct machine. Change into your CS 16 directory, create a lab05 directory and change into it. Remember that at any time, you can check what directory you are currently in with the command pwd.

Step 2: Create and Edit Your C++ Files

This week, you will need to create 3 files called change.cpp, reverseArgs.cpp, and multiply.cpp: Each corresponds to one of the problems listed below, which make up this lab.

This assignment consists of 3 problems, each of which is described below. The first and second are worth 40 points each and the third one is worth 30 points. Each should be solved in its own file and both must be submitted for full assignment credit.

NOTE: All these submissions will be checked by the automatic system on submit.cs AND by the instructor and TAs for further evaluation. Details below.

CHANGE.CPP

Write a program that tells what coins to give out for any amount of change from 1 cent to 99 cents. For example, if the amount is 86 cents, the output would be something like the following:

86 cents can be given as 3 quarters, 1 dime, 1 penny.

Use coin denominations of 25 cents (quarters), 10 cents (dimes), and 1 cent (pennies). Do not use nickel and half-dollar coins.

Your program should use the following function (among others):

void compute_coins(int coin_value, int& num, int& amount_left);
// Precondition: 0 < coin_value < 100; 0 <= amount_left < 100.
// Postcondition: num has been set equal to the maximum number
// of coins of denomination coin_value cents that can be obtained
// from amount_left. Additionally, amount_left has been decreased
// by the value of the coins, that is, decreased by
// num * coin_value.

For example, suppose the value of the variable amount_left is 86. Then, after the following call:

compute_coins(25, number, amount_left);

the value of number will be 3 and the value of amount_left will be 11 (because if you take 3 quarters from 86 cents, that leaves 11 cents).

Include a loop that lets the user repeat this computation for new input values until the user says he or she wants to end the program by inputting a zero (see example below).

Your program must use the compute_coins function declaration shown above. A program which does not will be awarded a score of zero, even if all tests pass.

A session should look exactly like the following example (including whitespace and formatting - note that there is no whitespace at the end of each of these lines and each printed line has a newline at the end), with all manners of different numbers for inputs and the output:

Also note that the words have to match the numbers (so singulars for quarter, dime, and penny are expected as appropriate for the case). This can be trickier than it looks.

REVERSEARGS.CPP

Write the program reverseArgs.cpp that takes command line input arguments and prints them back in reverse order. For example, if you ran the program as ./reverseArgs first_arg second_arg, you would get an output back of second_arg first_arg.

If you ran the program as ./reverseArgs I love gorgonzola cheese, but I hate toothpaste, you would get an output back of toothpaste hate I but cheese, gorgonzola love I.

If you ran the program with double quotes, then the words within should act as one unit. For example: ./reverseArgs I would rather be at "UC Santa Barbara" would output: UC Santa Barbara at be rather would I.

A session should look exactly like the following example (including whitespace and formatting - note that there is no whitespace at the end of each of these lines and each printed line has a newline at the end), with all manners of different numbers for inputs and the output:

MULTIPLY.CPP

For the 3rd program, you will write a simple program that multiplies two numbers provided as command line arguments. When it is complete, the program should take exactly two command line arguments that are integers, multiply them together, and print their product on the standard output.

If the number of arguments is not exactly two (other than the program name itself), a “Usage” message is printed. Hint: you may want to use cerr instead of cout here.

Here are some sample runs:

Step 3: Create a makefile and Compile the Codes with the make Command

In order to learn another way to manage our source codes and their compilations, we will first create a makefile and put in the usual g++ commands in it. Afterwards, whenever we want to compile our programs, the Linux command is a lot shorter. The use of makefiles will reveal itself to be very useful the more complex our programs and CS projects become.

Using your text editor, create a new file called makefile and enter the following into it:

all: change reverseArgs multiply

change:
	change.cpp g++ -std=c++11 change.cpp -o change

reverseArgs:
	g++ -std=c++11 reverseArgs.cpp -o reverseArgs

multiply:
	g++ -std=c++11 multiply.cpp -o multiply

Then from the Linux prompt, you can do one of two things: either issue separate compile commands for each project, like so:

$ make change

Or, you can issue one command that will compile all the projects mentioned in the makefile, like so:

$ make

If the compilation is successful, you will not see any output from the compiler. You can then run your programs, for example:

$ ./change

If you encounter an error, use the compiler hints and examine the line in question. If the compiler messsage is not sufficient to identify the error, you can search online to see when the error occurs in general.

Remember to re-compile the relevant files after you make any changes to the C++ code.

Step 4: Submit

Once you are satisfied that your programs are correct, it is time to submit them. Login at https://submit.cs.ucsb.edu, then navigate to “CS16_f16” and click on “lab05”. Then click “Make Submission”, and make your submission the same way as last week. Remember to submit all 3 of the .cpp files.

Please remember that you must submit the programs to obtain any credit for the assignment; just completing the programs is not enough.

Once you submit, you should see a page detailing your submission. The system will automatically grade your program and will show you the results on this page after a 1 minute delay.

You can alternatively submit your code from the command line (terminal) on any CS machine, including the Phelps lab machines or the CSIL server. You can use this method when logged in remotely. To submit the the three source files to this assignment by running the command:

$ ~submit/submit -p 572 change.cpp reverseArgs.cpp multiply.cpp

You can copy the URL shown in the output of the above and paste into a web browser to reach the submission result page.

Step 5: Check Submission Results

After the 1 minute delay, the submit system will show your score and give you feedback on your submission. Refresh the webpage after a minute to see this information.

You may submit this lab multiple times. You should submit only after local compilation does not produce any errors and runs as expected. The score of the last submission uploaded before the deadline will be used as your assignment grade.

Step 6: Done!

Once your submission receives a score of 100/100, you are done with this assignment.

If you are in the Phelps lab or in CSIL, make sure to log out of the machine before you leave. Also, make sure to close all open programs before you log out. Some programs will not work next time if they are not closed. Remember to save all your open files before you close your text editor.

If you are logged in remotely, you can log out using the exit command:

$ exit