CS120 Day 1: C & Unix Basics
-----------------------------
- review syllabus

- course prereqs: 
  - Java programming or equivalent
  - no knowledge of C or C++ expected

- big picture concepts to focus on
  - really understanding memory usage
  - testing & debugging
  - code refactoring
  - OO design
  - polymorphism

- quickie review of programming language types

- C "features"
	- obscure code
	- illicit hacking
	- system level programming
	- really efficient memory usage
	- shoot yourself in the foot

- different language versions evolved over time
- different implementations (compilers) based on platform/hardware

>>>>> FOCUS ON DIFFERENCES BETWEEN JAVA AND C <<<<<<

- read posted C tutorial to start

>>>> USE gpa.c as sample program (unfinished) <<<<

PROGRAMMING PROCESS ====================

- store source code in file.c
- create source code with editor (emacs, vi, etc.)
- compile & run 
	- gcc file.c -> creates a.out -> run with ./a.out
	- gcc -o file file.c -> creates executable file -> run with ./file
	
- explain .o files and compilation steps for C
	- pre-processing: include files, definitions
	- compile (program = source code -> assembly -> machine = object code)
	- link w/library routines
	- load into memory
	- execute = run in CPU

- preprocessor directives
	#include <lib.h>
	#define THING value	 - macro/constant definitions

- comments: /* long comment form */, // short end-of-line comment


DATA TYPES ===============================
- primitive data types 
    - not as strongly typed as Java
	- exact sizes of each are implementation defined! (platform dependent)
	- char,	short, int (default), long, float, double, long double
	- unsigned qualifier can apply to any (signed is default)
	- const qualifier (final in Java)

- variables are never initialized for you!!!

- booleans 
	- no data type in old C, use ints
	- bool type in c99 w/true, false
	- 0 is false, non-zero is true
	- use in all control structures
		
- ASCII characters, escape sequences
	- <ctype.h>
	- isalpha, isdigit, etc.
	- tolower, toupper

- arrays
	- declare: type var[CONST_SIZE]
	- declare w/init: type var = {val1, val2, ...};
	- indices start at 0
	- elements passed by reference to method

- strings
	- not primitive, not class, array of characters
	- special null character '\0' to terminate
	- "string literal"
	- no + operator concatenation
	- <string.h> for library functions
	- strlen(s) returns #chars before \0


OPERATORS ====================================
- operators
	- arithmetic
	- relational & logic
	- precedence
	- short-circuit evaluation
	- bitwise logical operators
	- bitwise shift operators
			

SIMPLE I/O ===========================
- #include <stdio.h>

- output
	- void putchar(char);
	- puts("some string");
	- printf("format string", args...);
		- formats: (Appendix B)
			%i %d %f %c %s %n %ld %lf
			%o octal
			%x hex
		- field widths
			%cols.decf - eg. %.2f, %.6f
			right justified by default
			use %- to left justify 
			- and cols works for %d and %s also
- input
	- int getchar()
	- EOF predefined constant for end of file


WORKING IN UNIX =====================

- give out class accounts
  - login
  - passwd to change password
  
- command-line environment
- two environment options: 
  - remote: ugrad network: ssh/putty into ugradx.cs.jhu.edu
  - local: virtualBox/Lubuntu

- basic file commands: ls, mkdir, cd, cp, mv, rm
- viewing files: cat, more, less
- printing: lp filename (check what default printer is)

- file hierarchy and shortcuts: ., .., ~

- use scp (secure copy) to copy from ugrad to local machine & vice versa
  > scp localfile joanne@ugrad3.cs.jhu.edu:remotepath
  > scp joanne@ugrad3.cs.jhu.edu:remotepath/filename localfile

- downloading a file from the web: wget http://someURL

- I/O redirection
  - use > to send output of any command to a text file instead of screen:
        ls -al >myfiles.txt
        ./a.out >output.txt
  - use < to get input for any command from a text file instead of keyboard:
        ./a.out <input.txt
  - can use both together