Description
1 Introduction
The operating system of a computer is the coordinator of all the computer’s activities, including memory
allocation, process switching, and file access. At Wake Forest University students typically use the Windows
operating system on their laptops. In CSC 112 you will use a version of Debian called Ubuntu on a remote
server. For this reason, this lab will introduce you to these environments for C++ programming. Specifically
this lab covers,
1. Login to your bally.cs.wfu.edu account.
2. Introduce the Linux environment: file structure and commands.
3. Create the directory structure required for this course.
4. Use Unix commands to copy/compile/execute an existing C++ program.
2 Logging into Your Account
This semester you will use bally.cs.wfu.edu, a Linux server hosted by the Computer Science Department,
to complete your lab assignments. When you access the server you’ll likely open at least two windows, one
for a command line (Xterm) and the other for an editor (sublime). To do this you may need to install and
configure a few applications. See the course web page for details about installing the software and logging
into your account.
3 Unix File Structure and Commands
“root”
/
home
djj
fulp
your name here
Grade
Example
Lab0
…
…
usr
include
local
bin …
Figure 1: Partial directory structure for your Linux system.
The Linux operating system is organized as a hierarchical file structure. As seen in figure 1, this structure
appears like the roots of a tree. At the top is the root directory, which is symbolized by a forward slash
/
1
. Beneath the root directory are all the other directories and files in the Unix system (this includes your
files). Therefore, each file and directory has a specific place in the file system, which is called the pathname.
Pathnames indicate the way through the file structure.
For example using figure 1, the path from root to your own directory path would be
/home/userName
1As discussed later, the forward slash serves two functions: represents the root directory, and separates names in a path
name (unlike DOS). Relax, it will only get more confusing
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This path is returned if you issue the present working directory command at the terminal prompt. To
determine the directory enter pwd at the prompt and hit Enter .
✷ Terminal ✷✷
> pwd
/home/userName
This directory is also called your home directory. Another example is the directory that contains the include
files necessary for compiling a C++ program. These files are located in /usr/include/. During the semester
you will create various files and directories off of your home directory. For this reason you must know a few
simple Unix commands, which are introduced in the next section.
3.1 Unix Commands and the CLI
official opening ceremony ribbb
Unix (Linux) commands provide a mechanism to interface with the operating system. These commands
allow a user to create files, move directories, compile programs, etc… On the server bally.cs.wfu.edu
there are approximately 3,408 commands available (hit the tab key twice and enter yes to see the list). Unix
commands (as well as file and directory names) are case sensitive; therefore, entering PWD at the prompt
will not return the current directory, you must enter pwd at the prompt. Below is a list of important Unix
commands you must know.
Command Description
pwd Returns the path name from root to the current working directory.
This is called the full path name.
ls Lists the current directory. There is a variety of command options
for ls. For example, ls -al provides detailed information about
each file in the current directory.
mkdir directoryName Creates a directory called directoryName.
rmdir directoryName Removes the directory called directoryName. Note the directory
must be empty.
cd pathName Change directory to pathName . Note that entering cd without a
pathName will return you to your home directory. Furthermore,
cd .. moves back one directory.
cp fileName1 fileName2 Copy file fileName1 to file fileName2.
rm fileName Erase file fileName . Once erased you can not get the file back.
more fileName View the contents of the file called fileName (if it is ASCII).
man commandName Provides a description of the Unix command commandName including syntax and options.
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The path or file name for any command will be relative to the current working directory. For that reason,
it is not always necessary to supply the full path name. For example using figure 1, suppose you are in the
directory usr and want to move to include. You could enter cd include, instead of supplying the full
pathname cd /usr/include
4 Creating Your CSC112 Directory Structure and
Compiling an Existing C++ Program
For this portion of the lab you will create two directories, copy a C++ program into your directory, compile
the program, then execute the program. For this class (CSC112), all programming assignments must reside
in certain directories for grading. This portion of the assignment will cover how these directories are created
using the commands in the previous section.
First, move to your home directory. To do this enter the cd command at the prompt. Issue a pwd
command to be certain you are in your home directory.
✷ Terminal ✷✷
> cd
> pwd
/home/userName
Now create a new directory called CSC112 off your home directory. Issue the following commands to accomplish this.
✷ Terminal ✷✷
> mkdir CSC112
Now list your home directory. You should see the directory you just created (among other files in your
home directory). All programs for this class will reside in this new directory. The program files for each
lab/assignment will be contained in a separate directory. For this lab, create a directory called Lab0 in the
CSC112 directory. To accomplish this, first cd to the CSC112 directory. Then create the Lab0 directory.
✷ Terminal ✷✷
> cd CSC112
> mkdir Lab0
4.1 Copy and Compile
A C++ program (source) file called hello.cpp is located at course web page. To obtain the file, you can
use firefox for a web browser (type firefox & at the command prompt). OK, that’s a lame way of doing it,
way too slow. You can actually copy the program from the web using wget command as follows.
✷ Terminal ✷✷
> wget www.cs.wfu.edu/∼fulp/CSC112/hello.cpp
After you have copied the file, place it in your Lab0 directory (use the mv or cp command if necessary). Then
compile and execute the program. The command to compile a C++ program is
g++ -Wall -pedantic -o executableName sourceName
Where sourceName is the C++ program (source) file and executableName is the resulting executable
file. For the hello.cpp compile the program so the resulting executable is called hello The g++ compiler
has more options, which will be introduced as they are needed. To run the program enter ./hello at the
prompt.
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5 The Grade Directory
“root”
/
home
your name here
CSC112
Lab0
Grade
Example
Lab0
…
Figure 2: Partial structure for your home directory.
Your home directory contains a Grade subdirectory. Inside this directory are other subdirectories for
each lab assignment this semester. This is depicted in Figure 2. Once you are done with an assignment, you
will copy your completed work to one of these subdirectories for grading. If you work is not in the correct
subdirectory by the assignment due date, then it will be considered late.
Assume you are currently in your CSC112/Lab0 directory and are ready to copy your work (lab0.cpp)
to your Grade/Lab0 directory. To do so you would enter the following command.
✷ Terminal ✷✷
> pwd
/home/yourLoginID/CSC112/Lab0
> cp lab0.cpp ../../Grade/Lab0
6 A Simple C++ Program
In this portion of the assignment you will write your own C++ program. To accomplish this you will need
to start a text editor. Although our Unix environment has multiple text editors installed, we will start with
edit. To start sublime enter sublime at the Unix prompt.
✷ Terminal ✷✷
> sublime
6.1 Program: Temperature Conversion
Create a new file called lab0.cpp in your Lab0 subdirectory. Then write a program that solves the following
problem. Be certain you follow the programming points at the end of this section.
Write a simple program that will convert temperatures in Fahrenheit to Celsius, or vice versa depending
on the user’s input. The equations you need are as follows, where c is the temperature in Celsius and f is
the temperature in Fahrenheit.
c = (f − 32) ×
5
9
f = c ×
9
5
+ 32
6.2 Program Description
Prompt the user to enter a temperature, which is a number followed by an upper case or lower case ‘c’ or
‘f’ for the scale. You may assume the number and the character will be separated by at least a space. If
the scale is ‘c’ then display the temperature in Fahrenheit. If the scale is ‘f’ then display the temperature
in Celsius. If the scale is neither ‘c’ or ‘f’ then display an error message.
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✷ Terminal ✷✷
> ./lab0
Enter a temperature (value and scale) -> 59 f
Converted temperature is 15 C
✷ Terminal ✷✷
> ./lab0
Enter a temperature (value and scale) -> 33 C
Converted temperature is 91.4 F
✷ Terminal ✷✷
> ./lab0
Enter a temperature (value and scale) -> 318 i
Error: scale must be C or F
6.3 Programming Points
You must turn-in an electronic copy of your programs. This must be done before the assignment due date.
Electronic copies will be submitted by placing the source file (lab0.cpp) in your Grade/Lab0 directory. You
must adhere to all of the following points to receive credit for this program.
1. Name your source (C++ program) file lab0.cpp
2. Program must compile without errors or warnings using the -Wall and -pedantic options
3. Global variables are not allowed. All variables must be declared within a function.
4. All prompts and output must appear as described. Please note the examples carefully.
5. All code must follow the style guidelines for this course and be documented.
7 Electronically Submitting Your Program
You must turn-in an electronic copy of your program. This must be done before the assignment due date.
Electronic copies will be submitted by placing the source file (lab0.cpp) in your ~/Grade/Lab0 directory.