CS 161 Lab 1

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Lab 1
In order to get credit for the lab, you need to be checked off by the end of lab. For nonzero 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.
(2 pts) Getting Set Up
These exercises need to be completed individually by each student. This is to ensure
that everyone gets setup properly! You can certainly ask your friend(s) questions! virtually☺
1. Log into TEACH to see if you have an ENGR account. If you do not have an ENGR
account, then you will need to create one by clicking on the link at the bottom of the login
page that says: Create a new account (Enable your Engineering resources).
2. Log on to the ENGR server through a secure shell. Depending on your operating
system, you need to go to the instructions for Windows or MacOS/Linux.
Windows Users:
Download a free Secure Shell (ssh). We will use the MobaXterm this quarter.
MobaXterm: http://mobaxterm.mobatek.net/download-home-edition.html (Use Installer
Edition, unless you are not using your own computer, and extract files in zip to not get a
bunch of messages about accessing files.)
Once you have installed MobaXterm, open MobaXterm. Go to Sessions -> New Session,
and click on the SSH icon.
Enter access.engr.oregonstate.edu as the remote host, and click on the Specify
Username checkbox to enter your username in the appropriate field.
Click on the Bookmark settings tab to save your session with a specific name, e.g. ENGR.
Lastly, click OK!!! ☺
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The ENGR session you just created will connect, and you will be asked to enter your
password at the prompt. **Note: You will not see anything as you type your password. This
is a security feature in Linux!!!
You will need an authentication for DUO Two-factor login, please read this information and
sign up here.
Or you can bypass the need for DUO by setting up SSH Keys, see instructions here.
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After a successful logon, press ENTER at the prompt below:
Terminal type? [xterm]
Then you get a prompt that looks something like this:
flip1 ~ 1%
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MacOS or Linux Users:
You have a terminal w/ ssh built into the OS. Open the terminal by going to Go -> Utilities -
> Terminal (on a Linux system, you might be able to click on the desktop and select
Terminal). At the prompt, type ssh username@access.engr.oregonstate.edu. (replace
username by your onid username)
The ENGR session you just created will connect, and you will be asked to enter your
password at the prompt. **Note: You will not see anything as you type your password. This
is a security feature in Linux!!!
You will need an authentication for DUO Two-factor login, please read this information and
sign up here.
Or you can bypass the need for DUO by setting up SSH Keys, see instructions here.
After a successful logon, press enter at the prompt below:
Terminal type? [xterm-256color]
Then you get a prompt that looks something like this:
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flip1 ~ 1%
Now, let’s enable the use of your Backspace key, so that you don’t get the pesky “^?” in your
text editor.
• Go to your Terminal Preferences under the Advanced tab and enable "Delete Sends
Ctrl-H".
3. Practice Linux Commands
• Listing the contents of a directory/folder.
At the prompt, type the following commands one by one to look at your files and directories
in your home directory. Note the differences on a piece of paper.
ls
ls -a
ls -l
ls –al
**Note: You should notice a . and .. directory listed. The . directory refers to your current
directory, and the .. directory refers to one directory above your current directory. The ~
refers to your home directory.
• Instructions for Unix/Linux commands.
UNIX/Linux provides you manual pages for the commands. You are encouraged to read
these manual pages when you have questions about a specific command or want more
details about the options to use with a command. Use the space bar to scroll forward
through the manual pages (one page at a time), press b to scroll backwards (one page at a
time), and press q to quit the manual page. You can also use the up and down arrow keys
to scroll forward and backward one line at a time, but who wants to do this☺
man ls
• Find Unix/Linux commands.
In addition, if you are not sure what a command is in UNIX/Linux, then you can find the
appropriate command using apropos and a keyword. For example, what are the UNIX/Linux
commands for editing a file, working with a directory, etc.
apropos editor
apropos directory
You may have noticed that you get more text than what can fit in your terminal window. To
view data a page at a time in your terminal, you can pipe the command contents through
another command called less. This will allow you to scroll through the pages using space
bar, b, and q just as you did with the manual pages.
apropos directory | less
• Directories/Folders.
Make a directory in your home directory named labs, and change into the labs directory.
mkdir labs
cd labs
Create a directory in your labs directory named lab1, and change into the lab1 directory.
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mkdir lab1
cd lab1
Make a note of your present working directory.
pwd
You can go back/up a directory by using two periods/dots together, and you can go back to
your home directory by using the tilde, ~. Use the pwd to confirm you are back in your home
directory.
cd ..
cd ~
pwd
Now, change into the labs/lab1directory by using your up arrow key to take you through the
history of commands you’ve used in the past. You should see the cd labs and cd lab1
command you typed earlier. You can also change directly into the lab1 directory by using
cd labs/lab1.
A good rule of thumb is to use pwd at any time to determine where you are, in case you
forget.☺ Also, don’t be scared to use ls as often as you need to see a listing of your
current directory!
• Creating Files.
Use the vim editor to create a C++ file containing your first C++ program.
vim hello.cpp
Below is an overview of vi/vim and a set of useful commands. **Remember you can man
vim to see the manual pages for vi/vim. In addition, I have provided a useful vim tutorial
under Useful Links on our Canvas website. One of the default editors that come with the
UNIX operating system is called vi (visual editor) or vim (visual editor improved). [Alternate
editors for UNIX include emacs and pico.]
The UNIX vi editor is a full screen editor and has two modes of operation:
• Command mode commands which cause action to be taken on the file, and
• Insert mode in which entered text is inserted into the file.
In the insert mode, every character typed is added to the text in the file; pressing the <Esc>
(Escape) key turns off the Insert mode.
Basic Commands (in command mode):
:w<Return> - write out modified file to file named in original invocation
:wq<Return> - quit vi, writing out modified file to file named in original invocation
:q<Return> - quit (or exit) vi
:q!<Return> - quit vi without saving the latest changes
:0<Return> - move cursor to first line in file
:n<Return> - move cursor to line n
:$<Return> - move cursor to last line in file
:set number<Return> - insert line numbers into vi file
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/search<Return> - find first occurrence of search from the location of cursor in
the downward direction
?search<Return> – find first occurrence of search from the location of cursor in
the upward direction
n – move cursor to next occurrence of last search (in direction of search)
j [or down-arrow] - move cursor down one line
k [or up-arrow] move cursor up one line
h [or left-arrow] move cursor left one character
l [or right-arrow] move cursor right one character
0 (zero) - move cursor to start of current line (the one with the cursor)
$ - move cursor to end of current line
^ - move cursor to the first non-whitespace character in a line
w - move cursor to beginning of next word
b - move cursor back to beginning of preceding word
u – undo whatever you last did
x – delete current character
dd – delete current line
yy – yank line and put into buffer for pasting
p – paste text in buffer to line below cursor
i – enter insert mode and enter text before the cursor
a - enter insert mode and append text after cursor
o - enter insert mode and enter text on line below cursor
<Esc> - get out of insert mode and enter command mode
Write the infamous “hello world” program as your first piece of C++ code. Use the style
guideline on the class website for suggestions on how to format your code:
http://classes.engr.oregonstate.edu/eecs/fall2019/cs161-001//161_style_guideline.pdf
 #include <iostream>
int main() {
 std::cout << “Hello World!” << std::endl;
 return 0;
}
• Compiling/Executing C++ Code.
Now, we will use the GNU C++ compilers on the server to compile your C++ “hello world”
program. Then, you will execute the compiled program.
g++ hello.cpp –o hello
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./hello
You can also compile/execute C++ code using Clang compiler:
clang++ hello.cpp –o hello
./hello
(4 pts) Answer Reflective Metacognitive Questions
Record your answers to the following questions in a word or text document on your computer to
submit at the end of lab. For each question, make a change to the hello.cpp file, recompile (g++
or clang++), and possibly execute the program (./hello) if there are no errors from the
compilation.
Question 1: What happens when you forget the semicolon at the end of the cout statement? Be
specific.
std::cout << “Hello World!” << std::endl
Question 2: What happens when you forget to include iostream, i.e. remove #include
<iostream> from the program? Be specific.
Question 3: What happens when you put “Hello World” on a new line? Be specific.
std::cout <<
“Hello World!” << std::endl;
Question 4: What happens when you put World!” on a new line? Be specific.
std::cout << “Hello
World!” << std::endl;
Question 5: What happens when you remove the << std::endl? What is the difference in
having it and not having it?
std::cout << “Hello World!”;
Question 6: What happens if you forget to include the main function? Note: Instead of
removing the lines from the file, comment them out using //. Put a // in front of the lines with int
main() {, return 0;, and }. Be specific.
(2 pt) Add a variable and reading input to the program:
Now, let’s add a variable (or a place to store information) in our program. We will create a place
to store an integer (or whole number). Then we will ask/prompt the user to enter a number, read
the input from the user, and display it back to the screen.
 #include <iostream>
int main() {
 int number;
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 std::cout << “Hello World!” << std::endl;
 std::cout << “Enter an integer: “;
 std::cin >> number;
 std::cout << number << std::endl;
 return 0;
}
Compile and execute your C++ “hello world” program again with the new changes.
g++ hello.cpp –o hello
./hello
For each question, make a change to the hello.cpp file, recompile (g++ or clang++), and
possibly execute the program (./hello) if there are no errors from the compilation.
Question 7: What happens if you mix the direction of >> with the cin? Be specific.
std::cin << number;
Question 8: Why do you need to create a variable to display a number entered by the user?
(2 pts) Upload Written Document (.doc or .txt) and Program (.cpp) to TEACH
Since you have to upload your assignments from your local computer or the ENGR server to
TEACH, then we should practice now☺ It is easy to upload files from your local computer to
TEACH, as long as you remember where you save it!!! ☺ However, it is not as easy for you to
upload files from the ENGR server to TEACH.
Two ways to upload the file from ENGR to TEACH.
• Transfer Files from ENGR to local computer
You can transfer the file to your own computer, then upload it to TEACH:
Windows Users: MobaXterm already has a sftp client installed. Notice the window pane on the
left with folders and files. You can drag and drop a file to your local desktop to select on
TEACH.
MacOS Users: (See “Map Network Drive” section below)
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OR
• Map Network Drive
You can map a network drive and choose the file from the mapped network drive. This allows
you to directly work off the server as if it were a disk drive on your computer. You can follow
these instructions to map a network drive for Windows or MacOS.
Windows:
http://it.engineering.oregonstate.edu/accessing-engineering-file-space-using-windows-filesharing
MacOS:
http://it.engineering.oregonstate.edu/accessing-engineering-file-space-using-os-x-smbcommand
If you want to use the drive off campus, then you must download the Cisco VPN Client from
OSU: http://oregonstate.edu/helpdocs/osu-applications/offered-apps/virtual-private-network-vpn
**NOTE: You may want to put these programs on a flash drive to carry with you in your
backpack. This will help you get around from any computer without needing your laptop all the
time.