This assignment deals with makefiles. I strongly recommend that you read the entire assignment through once, including the Important Notes section , before starting. Create a directory...

I strongly recommend that you read the entire assignment through once,
including the Important Notes section, before starting.

1. 
   

   Create a directory
   ~/UnixCourse/makeAsst. Within that directory, create a pair of subdirectories,
   project1
   and
   project2
   

   
   

   Copy the .h and .cpp files from your earlier “Compilation” assignment (should be in
   ~/UnixCourse/compileAsst) into your
   project1directory.

   
   

   Copy all files from the
   ~cs252/Assignments/cpp2html/
   directory into your
   project2
   directory.

   
   


2. 
   

   In
   project1, create a makefile that will compile
   guess.cpp
   and
   yesno.cpp
   to produce the files
   guess.o
   and
   yesno.o, and will link those two
   .o
   files to produce an executable program named
   guess.

   
   

   This should occur in 3 discrete steps (compiling
   guess.cpp, compiling
   yesno.cpp, and linking the results).

   
   

   You may produce your makefile “from scratch” or as a modification of my self-updating makefile for single-program projects.

   
   

   Verify for yourself that the
   make
   command (with no arguments) does produce the desired program. (You can do this by issuing the
   make
   command directly at the command line, or via emacs’
   M-x compile
   command.)

   
   

   Once you have successfully got
   make
   to build the project, run it again. Note that
   make
   realizes that the project is already up-to-date and does not rerun any of the compilation commands.

   
   

   One big reason that we use
   make
   is because, on large projects consisting of many, many files, we want to avoing recompiling
   everything
   after changing just one or two files.
   make
   looks at what files have changed (by checking their modification dates - the dates you see when you do a
   ls -l
   command) and figures out the minimal number of steps required to rebuild the project based upon what has actually changed.

   
   

   Now make a trivial change to either
   guess.cpp
   or
   yesno.cpp, but not both. For example, add a blank line at the beginnign or end of the file. Then run
   make
   again and verify that your makefile really does recompile only the changed file.

   
   

   You can simulate a change to a file without actually changing its contents via the
   touch
   command, which alters a file’s modification date without altering the contents of the file. For example, if you do

   
   

   
   touch guess.cpp
   

   
   

   and then run
   make
   again, it should recompile
   guess.cpp, but not
   yesno.cpp.

   
   


3. 
   

   The code in
   project2
   is for a program that formats C++ code into HTML for presentation in a webpage. For example, here is the web page produced by running the command

   
   ./cpp2html < ~/unixcourse/compileasst/guess.cpp=""> guess.html

   

   (once the program has been successfully compiled, of course).

   
   

   This program would have been a massive undertaking to write in pure C or C++, but was actually put together quite quickly using a software tool called “flex” that was originally developed for use in building compilers. Whats interesting about
   flex
   is that it actually writes out the program code for a substantial portion of a compiler (the “scanner” or “lexical analyzer”) from a (relatively speaking) simple description of what the language being processed
   looks
   like.

   
   

   The steps necessary to produce this program are:

   
   
   
   
   1. 
      

      Compile
      cpp2html.c
      to produce
      cpp2html.o. (
      Important:
      the source code in this project is C, not C++, and so must be compiled and linked with
      gcc, not
      g++.)

      
      
   
   
   2. 
      

      Run the command

      
      flex cppscanner.l

      

      to produce the file
      lex.yy.c
      from the language description in
      cppscanner.l.

      
      
   
   
   3. 
      

      Compile
      lex.yy.c
      to produce
      lex.yy.o. (This often produces a warning message about extra tokens. Ignore it.)

      
      
   
   
   4. 
      

      Link the the
      .o
      files to produce an executable program named
      cpp2html
      

      
      
   
   
   
   

   Write a makefile that will carry out these steps. Your makefile should result in only the minimum required amount of steps when any input file to this process is changed. (Note: you will probably
   not
   be able to base this makefile upon my self-updating makefile as in the earlier part of the assignment. Instead, you will probably find it necessary to write this one from scratch.

   
   


4. 
   

   Give the command:

   
   ~cs252/bin/makeAsst

   

   to complete the assignment.