Linux/g++: Maze solving in CSE326

Linux machines at U. W.

• Machine Names: Ceylon, Sumatra, Fiji, Tahiti• http://www.cs.washington.edu/lab/facilities/instr-l

abs.html• Access

– Use X-terminals in back of Sieg 329 (click on one of the linux machine names)

– Use Windows machine, ask someone in lab for help

Make project directory

More UNIX commands are at: http://www.cs.washington.edu/education/courses/cse326/00wi/unix/unix.html

Look at supplied files

d????????? means it’s a directory. Ignore RCS (not mentioned in projectdescription)

Copy FilesOops,forgotthis.Even TAsmakemistakes

Interlude: ‘man’

Keys:q – exit manPage UpPage Down

The command:apropos copyFinds all man pages that containthe word “copy” in theirdescriptions. Useful for findingout about a command.

Look at files in my dir

My files are read-only‘w’ heremeans Ican write tothe files,but no-oneelse can

chmod (thanks to Nic Bone)> I'm having trouble understanding the man files. How would I change permission to> -rwxr--r--> > What's the syntax?The easy-to-remember way to do this is to type:% chmod a+r file% chmod u+wx file% chmod go-wx file

Meaning of the symbols:r: read w: write x: execute u: user g: group o: other a: all three (u, g, and o)+: add this permission-: remove this permission

You can also set the permissions with one command using a numeric code of three numbers in the range 0-7. The first number corresponds to user permissions, the second to group permissions, and the third to other (or world) permissions. Read permission is +4, write permission is +2, and execute permission is +1. So to change permission to -rwxr--r--, we would type:% chmod 744 fileNic.

How to make runmaze (the program)

Test run

./ is important. By default, Linux won’t search the currentdirectory for a program. So you have to explicitly tell it(eventually, you can change your PATH environment variable)

< means get the input from the file to the right (inputs/maze1.txt), instead of the keyboard. If you don’t put this in, runmaze willexpect you to type the maze in on the keyboard – quite a hassle!

Run sample solution

Run runmaze with visualization

What we type:

Extra visualizationwindow pops up(only implementedon Linux)

Edit runmaze.cpp – forgot &

Darn, nowwe lost thisshell untilwe closeemacs

Edit runmaze.cpp

Current line number

Emacs keys

• CTRL-X S (hold down control for both letters)– Save your work

• CTRL-X C– Exit emacs

• CTRL-G– Abort current command (if you accidentally typed something wrong)

• More:– (Quick intro)

http://www.cs.washington.edu/education/courses/cse326/00wi/unix/emacs.html

– (official documentation) http://www.lns.cornell.edu/public/COMP/info/emacs/emacs_toc.html

Simple change to runmaze.cpp

Change

Re-make program

Run re-made version

Intro to make – project file dependencies

runm aze

runm aze.oM aze.o

SquareM aze.oO ther

object files

runm aze.cpp

M aze.cppSquareM aze.cpp

O ther .h,.cpp files

M aze.h

SquareM aze.h

BTW : This is a graph, and m ake w ill perform a "TopologicalSort" to figure out in what order to build the files.

2 lines from Makefile

runmaze : runmaze.o MazeRunner.o RandomMazeRunner.o Maze.o SquareMaze.o VisualizeSquareMazeRunner.o GPKernel.o

g++ -o runmaze -g runmaze.o MazeRunner.o RandomMazeRunner.o Maze.o SquareMaze.o VisualizeSquareMazeRunner.o GPKernel.o -L/usr/X11R6/lib -lX11

runmaze (executable file) is dependant on a bunch ofobject files

If runmaze doesn’t exist, oris out of date (relative toobject files), here’s how tobuild it

WARNING: this is a tabcharacter. It has to be tab,and can’t be spaces. Thoseare the rules.

g++ linking command line

g++ -o runmaze -g runmaze.o MazeRunner.o RandomMazeRunner.o Maze.o SquareMaze.o VisualizeSquareMazeRunner.o GPKernel.o -L/usr/X11R6/lib -lX11

• -o runmaze– Call the output file ‘runmaze’ (instead of a.out, which is the

default)

• -g– Include debugging information, so you can use a debugger

• -L/usr/X11R6/lib -lX11– Include X-Windows libraries (for visualization part)

2 lines for runmaze.cpp (well, technically runmaze.o)

runmaze.o : runmaze.cpp Maze.h SquareMaze.h MazeRunner.h RandomMazeRunner.h VisualizeSquareMazeRunner.h

g++ -Wall -c -g runmaze.cpp

The object file runmaze.odepends on runmaze.cpp +some .h files

The infamous tabcharacter strikesagain!

If runmaze.o doesn’t exist, or is out of daterelative to the files past the colon ( : ), here’show to build it with g++.

g++ compiling flags

• -c– Only compile, don’t link – we’ll let make decide when to link.

• -Wall– g++ will give us all of the Warnings it can think of. Maybe it’ll

help us find a bug quickly.

• -g– Add debugging information.

Is this the g as in –g? Who knows?

So you want to add a .h file• Add it to every .o/.cpp that #includes it, directly or

indirectly.

runmaze.o : runmaze.cpp Maze.h SquareMaze.h MazeRunner.h RandomMazeRunner.h VisualizeSquareMazeRunner.h Fictitious.h

g++ -Wall -c -g runmaze.cppMazeRunner.o : MazeRunner.cpp Maze.h MazeRunner.h Fictitious.h

g++ -Wall -c -g MazeRunner.cpp

RandomMazeRunner.o : RandomMazeRunner.cpp Maze.h MazeRunner.h RandomMazeRunner.h

g++ -Wall -c -g RandomMazeRunner.cpp

But RandomMazeRunner.cpp doesn’t #include Fictitious.h(in our example)

Adding a .cpp file

runmaze : runmaze.o MazeRunner.o RandomMazeRunner.o Maze.o SquareMaze.o VisualizeSquareMazeRunner.o GPKernel.o Bogus.o

g++ -o runmaze -g runmaze.o MazeRunner.o RandomMazeRunner.o Maze.o SquareMaze.o VisualizeSquareMazeRunner.o GPKernel.o Bogus.o -L/usr/X11R6/lib -lX11

Bogus.o : Bogus.cpp Bogus.h Maze.h MazeRunner.h

g++ -Wall -c -g Bogus.cpp

Add .o file todependencies ofexecutable program

Also, add .o file tolist of files to linkin (must do both)

Tell make how tomake Bogus.o

Debugging

• Zasha recommends: – add print statements (or cout<<) so you can see what your

program is doing.

– Make them check a global variable (doDebug), so you can turn them off & on (to turnin for grading)

– Learn debugger later.

• Or – use gdb (see below)

– use xxgdb (has dinky graphical user interface)

start it/set a couple of breakpoints

break gdbSquareMaze::getStartMazeNodeis the form for putting a breakpoint on a C++ class method.

Run program in gdb

To see more commands, the help command ishelpor look at the extra information pointers near the beginning of these slides.

More info

• 326 Computing page (more info on these tools)– http://www.cs.washington.edu/education/courses/cse326/00wi/co

mputing.html

• GNU Info pages– http://www.lns.cornell.edu/public/COMP/info/

• Friendly people in lab / other students

• man command

• osmosis