I. compiling C++ programs (DD 1.12-13, 1.14-16)
 A. compilers vs. interpreters
-------------------------------
    COMPILERS vs. INTERPRETERS


  (Scheme program)  -----------> output
                    interpreter


  {C++ program}
       |
       | compiler
       |
       v
   [exectuable]      ----------> output
                       machine
-------------------------------
 B. phases of compilation (DD fig 1.1)
  1. preprocessing and compiling
------------------------------
  IMPORTANT PHASES OF COMPILATION

% g++ -ansi -pedantic -Wall prog.C


     {prog.C}
        |
	| preprocessor
	|
	v
     {prog.C with #include files
               and macros expanded}
	|
	| compiler proper
	|
	v
     [a.out]

% ./a.out
Welcome to the world of compilation!
--------------------------------
	what would change if the program was named myprog.C?
--------------------------------
% g++ -ansi -pedantic -Wall \
          -o prog.exe prog.C
% ./prog.exe
Welcome to the world of compilation!
--------------------------------
-------------------------
    SHELL SCRIPT FOR CALLING g++

The command
   /home/cs228/public/bin/ansicpp
can be used instead of
  g++ -ansi -pedantic -Wall
--------------------------
--------------------------
% ansicpp -o prog.exe prog.C
% ./prog.exe
--------------------------
	what would change if the program was named myprog.C?
 C. linking
-----------------------------
        PROBLEM

Write a program to input a number
and output its cosine.
------------------------------
----------------------------
    HEADER FILES and LINKING
        SUMMARY

% ansicpp -o cosine.exe cosine-main.C -lm

  /usr/local/lib/g++-include/iostream.h
                             math.h
  {cosine-main.C}
        |
	| preprocessor
	|
	v
  {cosine-main.C
            with iostream.h and math.h}
	|
	| compiler proper
	|
        v
  {object file} and /usr/local/lib/libm.a
        |
        | linking loader
        |
	v
  [cosine.exe]  ---------> output
                machine

% ./cosine.exe
Number? 3.14159
-1
----------------------------
	questions about this?
 D. separate compilation (if time)
 E. making own header file
-----------------------------------
  SEPARATE COMPILATION SUMMARY

% ansicpp -c cosine-main.C

  /usr/local/lib/g++-include/iostream.h
                             math.h
  ./prompt.h
  {cosine-main.C}
        |
	| preprocessor
	|
	v
  {cosine-main.C with iostream.h, math.h
                 and prompt.h}
	|
	| compiler proper
	|
        v
   cosine-main.o


% ansicpp -o cosine.exe prompt.o \
                        cosine-main.o -lm

  prompt.o, cosine-main.o 
                and /usr/local/lib/libm.a
        |
        | linking loader
        |
	v
  [cosine.exe]  ---------> output
                machine
-----------------------------------
	what if our program also involved graphics.C and graphics.h?
 F. for more info