CS 161 Lab 3

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Lab 3
Get checked off for up to 3 points of incomplete work from the previous lab within the
first 10 minutes of lab.
Each lab will begin with a recap of last lab and a brief demonstration by the TAs for the
core concepts examined in this lab. As such, this document will not serve to tell you
everything the TAs will in the demo. It is highly encouraged that you ask questions and
take notes. In order to get credit for the lab, you need to be checked off by the end of
lab. For non-zero labs, you can earn a maximum of 3 points for lab work completed
outside of lab time, but you must finish the lab before the next lab. For extenuating
circumstance, contact your lab TAs and Instructor.
In this lab, you can form a group of 2-3 individuals. You must be checked off together as a
group at the end of the lab. Although you perform tasks as a group, ensure that you
understand the work and ask questions to TAs as needed.
(2 pts) Review from Lab #2
1. The following are some of the most commonly used Linux commands. Provide a definition
for each.
rm, cp, mv, man
2. Using the above commands, outline the following tasks:
• Copy contents of one file, assign1.cpp, to another, temp.cpp, in the ~/assign
directory, when you are currently in the ~/assign/assign1 directory.
• Delete a file, temp.cpp, from the ~/assign directory, assume you are in your home
directory (~).
3. The following are some of the most common commands in vim. Provide an explanation for
each.
:set number
Part I – Vim/Linux Commands
(2 pts) More vim commands
First, create a lab3 directory in your labs directory, and change into the lab3 directory.
cd labs
mkdir lab3
cd lab3
Now, let’s practice using the vim editor following the instructions below. (If needed, refer to Lab
#1 for a reference guide to the basic commands)
1. Open a test file for practice – vim_test.cpp
2. Save the file using – :w <Press Return>
3. Go into insert mode by pressing i
4. Type the standard input/output header and main function in your test.cpp file.
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5. Get out of insert mode by pressing <Esc>.
6. Show the line numbers in vim by typing :set number
7. Go to the third line (or whichever line has main) in your code by typing :3
8. Delete this line of code by typing dd
9. Put the line of code back underneath the first line by moving your cursor to the top line
and typing p
10.Redo the delete by typing u to undo the paste.
11.Paste the line back using p
12.Now, copy the line of code by typing yy (If you want to copy >1line, you type one less
than the number of lines you want to copy after the y, i.e. y4 copies 5 lines) 13.Paste the
line of code by moving your cursor to a line and typing p
14.Undo the paste by typing u.
15.Try using the j, k, h, and l keys to move around the screen. You can also use the arrow
keys, but these don’t always work.
16.Try searching for “main” in vim with /main.
17.Go back into insert mode, i, and type some random letters, dkfjdsl, then press to go
back into command mode.
18.Use the x to delete all the characters from this random string you typed.
19.Press i to begin typing text again.
20.Now, write a small program:
• Ask the user if she/he likes vi as an editor.
• Read the 0 or 1 integer value from the user
• If the user says true, then display a message, “You love vi!”
• If the user says false, then display a message, “You hate vi!”
21.Now, press to get back into command mode, and go to the first line in your program by
typing :0.
22.Then, type =G to auto indent your program. You can set the number of spaces you
prefer by typing :set sw=3, then you want to auto indent again, =G. (If you want to auto
indent while you type, then use :set cindent)
23.You can change your color scheme or background by using one of these commands:
:colorscheme evening
:set background=dark
24.Now, write and quit the file by typing :wq Linux and vim cheat sheet to help you
reference some of these commands quickly:
http://classes.engr.oregonstate.edu/eecs/winter2020/cs161-010/CheatSheet.pdf
In the next lab you will add some of these useful commands to a vi system resources
file.
STOP: You can do Design and Implementation with the same group
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Part II – Password Generator
(2 pts) Design
Design is very important when developing programs and there are a variety of ways to
approach it. You may draw pictures, write it out in prose or structured text, use pseudo code,
and more! The point of design is to give you a blueprint to follow while you are coding. This
saves time debugging your program as you can catch mistakes early. It is better to spend one
hour of designing than it is to spend five hours debugging.
For this lab you must design a solution to the following problem statement. You will implement
your solution.
Problem Statement
A good password has many requirements. Humans have a hard time meeting these
requirements left to their own devices. You are tasked with creating a program that will
generate a password based on what the user wants in the password.
The user should be able to choose if they want a password with:
• letters
• upper case
• lower case
• numbers
The user should also provide the length of the password and how much of the password
should be composed of their selections. It is your choice to generate either in order or out of
order (see below).
For example:
Welcome to Password Creator!
How long do you want the password to be? 10
Do you want letters (0-no, 1-yes)? 1
Do you want uppercase letters (0-no, 1-yes)? 1
How many characters of the password should be uppercase? 2
Do you want lowercase letters (0-no, 1-yes)? 1
How many characters of the password should be lowercase? 10
Exceeds the length of the password!!!
Would you like to create another password (0-no, 1-yes)? 1
How long do you want the password to be? 10
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Do you want letters (0-no, 1-yes)? 1
Do you want uppercase letters (0-no, 1-yes)? 1
How many characters of the password should be uppercase? 2
Do you want lowercase letters (0-no, 1-yes)? 1
How many characters of the password should be lowercase? 4
Do you want numbers (0-no, 1-yes)? 1
How many characters of the password should be numbers? 4
Your random password is: ACbzdf1254 or AtCde1z254 (either would be acceptable
passwords)
Would you like to create another password (0-no, 1-yes)? 0
You need to generate characters and numbers for the password length specified by the user.
Therefore, you need a way to repeat generating random numbers and characters. You could
use a while loop, but it would be more appropriate to use a for loop.
The while loop is very much like an if statement, but it continues to repeat a block of code
while the condition is true, instead of doing it only once.
cout << “Enter a number greater than 1: ”;
cin >> input;
while(input<=1) {
cout << “This is not a good number!” << endl;
cout << “Enter a number greater than 1: ”;
cin >> input;
}
//now we know we have good input greater than 1
The for loop looks very different, and it is used to repeat something a specific number of times,
e.g. we want to loop through characters and numbers for the password length specified by the
user.
for(int i=0; i < pass_length; i++) {
//write code you want to repeat inside here
}
This is what is going on with the pieces of information in the for loop:
Step 1: create and initialize a counter variable i
Step 2: check if the counter variable i is less than pass_length
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Possible Step 3: do what is in the curly braces and part of the for loop
Possible Step 4: increment the counter variable i using i++
Possible Step 5: go back to Step 2 to see if the counter variable i is less
than pass_length
Possible Step 6: do not repeat and go to the bottom of the for loop
(4 pts) Implementation
Your design must be checked off by a TA before proceeding to code.
In your implementation, you must use the ASCII chart, and you must use rand() and srand() to
generate random values. Think about how we used rand to get a range of numbers in class.
Notice characters and numbers are in ranges in the ASCII chart: http://www.asciitable.com/
Show your completed work to the TAs for credit. You will not get points if you do not
get checked off