CSCI 160 Lab exercise 1, part 2 (take-home)

CSCI 160 Lab exercise 1: part 2

As with part 1, there are several key syntax elements you'll need to be familiar with. The core part 2 syntax elements can be found here.

For part 2, you'll be following similar steps as in part 1 except that you'll be creating a labex1 (instead of labex0) and you'll be writing the entire C++ program (your starting labex1.cpp file will just contain a single comment).

Refer back to the part 1 instructions if you forget the specifics of different steps.

Open the powershell window
ssh into your csci account
obtain the csci160/labex1 content using the make160 makefile
cd into your csci160/labex1 directory
use ls to see which files are present (hopefully a makefile and labex1.cpp)
edit the labex1.cpp file, creating source code to match the objectives described below
save and exit the editor
compile the program using make
repeat the edit/save/compile cycle until it compiles cleanly
try a test run of your revised program, and repeat the edit/save/compile/test cycle until you get the desired behaviour
make sure your program follows the course code standards
submit the lab (again, it's ok to submit multiple times if you revise the .cpp file more later)

labex1.cpp objectives

The objective for this exercise is to create and submit a complete and correct C++ program, adhering the the course code standards, with the following behaviour:

The program is intended to calculate and display the vote share of three parties in an election, as a percent of the total votes cast, and also to calculate and display the percent of people who actually voted.
The program stores a constant to represent the number of eligible voters, currently 16,164,886.
The three parties in the election are Hodunk, Zaford, and Scav (aside: never pick names at the last minute when you're running short on imagination).
The program prompts the user to enter the number of votes entered for the Hodunk, reads this and stores it. (No error checking is required on the validity of the user response.)
The program prompts the user to enter the number of votes entered for the Zaford, reads this and stores it. (No error checking is required on the validity of the user response.)
The program prompts the user to enter the number of votes entered for the Scavs, reads this and stores it. (No error checking is required on the validity of the user response.)
The program then calculates and displays the percent of total votes that went to the Hodunk, followed by the percent of total votes that went to the Zaford, followed by the percent of total votes that went to the Scavs, followed by the percent of eligible voters who actually voted.
Any percentages should be displayed in a format with exactly 2 digits following the decimal place, such as 9.31% or 27.84%.

Note: you may use either the iostream (cin/cout) or the cstdio (scanf/printf) approach for I/O, but pick one approach or the other, don't mix and match.

Suggested (iterative) development process

I strongly recommend adding and testing small parts of the program at a time, e.g.

First, edit the labex1.cpp to initially contain just the basic program structure (the #include and a main routine that contains nothing but the return 0 statement).
Get that to compile and run cleanly (it does nothing when it runs so far).
Next, add your constant and variable declarations and initialize them.
Again, get that to compile and run cleanly (it still does nothing).
Next, add printfs that simply print the value of each variable.
Again, get it to compile and run cleanly (not too interesting yet, but we can see that our code is working as expected so far).
Keep repeating this approach - add and debug one small chunk of functionality at a time. We are incrementally getting closer and closer to the desired results, while knowing that what we've written so far actually works.
Many people tend to sit down and attempt to write the entire program at once, then try to compile it. Often there are many conflicting syntax and logic errors within the code that are far more difficult to track down than they would be if we took the incremental approach.
(This effect gets more and more extreme as we work on larger and more complex programs, and you'll find your own personal balance on how large or complex the individual increments should be.)

Remember you must be in the correct directory, e.g. csci160/labex1, whenever you are working on the program, otherwise the necessary makefile and source code files are not present.
If you're unsure which directory you are in, enter the command
pwd
If you find you are in an incorrect directory then you can jump directly to the labex1 directory using the following command:
cd ~/csci160/lab1