[ summary | part a | part b | part c | part d | how to submit | grading ]
| Summary. |
For homework #0, you will fetch a source distribution that we have prepared. Next, you will trivially modify a simple hello world C application, use "make" to compile it, and run it to learn the magic code. You will also run a tool that checks your code for memory leaks. Finally, you will package up and submit your code.
As you can probably tell, the real goal of this homework is to make sure that all of the course infrastructure is working for you.
| Part A -- Fetch the code |
Overview
For this quarter, you'll fetch code from the CSE file system using scp. The code is packages as a "gzip'ed tar archive" so you'll need to un-gzip and un-tar it to produce your working directory. Once you've done that, you'll have the homework files and can edit them locally until ready to turn them in. We'll use the course drop box for turn-in.
You may want to use some source control system to help manage your files, and to provide a crude form of backup for them. Popular options are git and subversion.
Fetch the code
In the directory where you want to create a directory named hw0 containing your code:
bash% # note the period at the end of the command line bash% # replace username with your CSE login name bash% scp -r username@attu.cs.washington.edu:/cse/courses/cse333/13au/hw0.tar.gz .
Expand the tar file
First, have a look at what is about to happen:
bash% tar tzf hw0.tar.gz hw0/ hw0/hello_world.c hw0/.gitignore hw0/Makefile LICENSE.TXT bash%The files listed will be created when we expand the tar file. The paths are relative to the current working directory. So, file LICENSE.TXT will be created in the current working directory, as well as subdirectory hw0 and the files it contains.
bash% # expand the tar file bash% tar xzf hw0.tar.gz bash% cd hw0
| Part B -- edit, compile, and run hello_world |
In the hw0 directory, type make. This command will use the instructions in file Makefile to compile the hello_world application using the gcc compiler. Then run hello_world by typing the command ./hello_world. You should see one line of output from running the program:
bash% make gcc -g -Wall -O0 -c -std=c99 hello_world.c gcc -g -Wall -O0 -o hello_world hello_world.o bash% ./hello_world The magic code is: <xxxxx> bash%
for some <xxxxx> we're not telling you here.
Now, edit hello_world.c using your favorite Unix-based editor (mine is emacs), and change the printf so that it instead says:
bash% ./hello_world The magic word is: <xxxxx> bash%
Execute make to rebuild, and then re-run hello_world to make sure it does what you expect.
| Part C -- experience the gdb debugger |
You're unlikely to have any run time bugs in this homework, but let's use the debugger so that you know what it can do. Here is a session that launches the debugger, sets a breakpoint on source line 27 of hello_world.c, prints the values of a couple of variables and an expression, prints a "backtrace" of the stack (showing the sequence of procedure calls that led to executing line 27 of hello_world.c), and then continues execution. Type the italicized lines.