1. Object Oriented Programming COP3330 / CGS5409

2.  Compiling with g++  Using Makefiles  Debugging

3.  The base command for the Gnu C compiler is "gcc"  The base command for the Gnu C++ compiler is "g++"

4.  To compile a program that is in a single file, the easiest compilation uses the command format: g++  Where the filename ends with ".cpp“  Example: g++ prog1.cpp

5.  To invoke the Compile stage, which translates source code (.cpp files) into object code (.o files), use the -c flag. Format: g++ -c  To name a target (something other than the default filename, use the -o flag. Format: g++ -o

6.  g++ -o yadda.o -c fraction.cpp ◦ This command invokes just the compile stage on fraction.cpp, but names the object code file "yadda.o" (instead of the default "fraction.o").  g++ -o bob.exe circle.o main.o ◦ This command links the two object code files ("circle.o" and "main.o") into an executable, called "bob.exe" (instead of the default "a.out").  g++ -o myProgram thing.cpp main.cpp ◦ This command compiles and links (since -c not used) the code files "thing.cpp" and "main.cpp" together into the executable program called "myProgram".

7.  Source code is just text!  For the purposes of assignments, ANY text editor can be used to  Practice with at least one Unix text editor create code files ◦ For unix beginners, "pico" is recommended, due to easy learning curve. ◦ Emacs, Vim, MUCH more powerful

8.  Understand how to log into both CS machines: ◦ linprog.cs.fsu.edu ◦ program.cs.fsu.edu  Use SSH (Secure SHell) client to login  Files created on a windows machine can be FTP-ed to CS accounts with the SFTP feature built into the SSH software

9.  Usage: sftp [username@]hostname  get filename- retrieve remote file  put filename- upload local file  Standard Unix commands: ◦ cd, ls, pwd, chmod, rename, rm, mkdir, rmdir, help, quit  Alternatively, GUI File Managers ◦ WinSCP - Free Windows client with SFTP capability WinSCP ◦ FileZilla - Open source cross-platform GUI client FileZilla

10.  Unix system has what is called a ‘make’ utility  Configuration file to assist with compilation  Simple text file, should be named either ‘makefile’ or ‘Makefile’

11.  Idea of the ‘target’ ◦ What is able to be ‘made’?  Dependency list ◦ What needs to be re-made each time?  Command list, and formatting ◦ i.e. it must be preceded by a single ‘tab’ character  Extra targets, like ‘clean’, for cleanup ◦ target that lists a cleanup command (like the remove ‘rm’ command)  More than one target ◦ placing a target like ‘all’ at the top, and listing the executables made by the file as the dependency list

12. # This is a comment line # Sample makefile for fraction class frac: main.o frac.o g++ -o frac main.o frac.o main.o: main.cpp frac.h g++ -c main.cpp frac.o: frac.cpp frac.h g++ -c frac.cpp clean: rm *.o frac

13. frac: main.o frac.o g++ -o frac main.o frac.o  Specifies ‘frac’ as the target  Depends on main.o and frac.o  If either of these files changed since the last build, then ‘frac’ must be rebuilt  Links two object code files together into a target executable called ‘frac’

14. main.o: main.cpp frac.h g++ -c main.cpp  Specifies how to built the target ‘main.o’  Depends on main.cpp and frac.h  If either file changes, main.o must be rebuilt  Uses normal g++ commands for the compile stage

15.  Any section can be invoked specifically with the command: make  For instance, to build only the ‘frac.o’ target, use: make frac.o

16. clean: rm *.o frac  The target name is ‘clean’  Executes the remove command (‘rm’)  Removes the object code file(s) and the executable(s) from the current directory

17.  Compilation errors -- usually syntax errors, undeclared variables and functions, improper function calls.  Linker errors -- usually involve undefined functions or multiply-defined functions or symbols  Run-time errors -- two varieties. ◦ Fatal -- cause program to crash during execution ◦ Non-fatal (or logical) -- don't crash the program, but produce erroneous results.

18.  Compile stage errors: These are errors that will be reported by the compiler, which usually provides a filename and line number indicating where it ran into trouble, for each error reported.  Linking stage errors: These errors, also reported by the compiler, do not usually contain line numbers, since the linker works on object code, not on the original source code.  Run-time errors: These must be tested while running a fully-compiled program.

19.  Always start at the top of the list of errors. Fix the first error, then recompile and see what is left.  If a list of errors is too long, compile and debug one file at a time.  When searching for an error, start with the indicated line number, but also look in the vicinity (usually previous lines) for the possible error.  Compile portions of programs as you go -- don't wait until the program is fully written to do the first compile!

20.  Learn what kinds of problems cause linker errors (usually problems with agreement between definitions and calls).  Linker errors usually specify some kind of symbol (used by the compiler), which often resembles a function or variable name. This is usually a good clue.  Learn about good compilation techniques and pre-processor directives that help avoid linker errors.

21.  To catch fatal errors, try to wedge the mistake between extra printout statements to locate the cause.  To catch logic errors, place extra printout statements in code while testing (to be removed in the finished version). Especially, print out values of internal variables to locate computation problems.