Lecture Outline for Week 1

I. Class Introduction
	- Course info sheet
	- Prerequisites : CSC148, MAT133

II. CDF accounts
	- Accounts listed on class home page
	- Machine location: Engineering Annex rooms 107, 201, 203, 206
	- Door code: see instructor
	- Printer limit of 300 sheets per term!
	- Be a good user - don't play games when system is busy
	- faq
		- lists useful info
		- describes how to connect from home 
	- rules
		- CDF account rules

III. Unix
	- see A Students Guide to CDF
	- man - "manual"
	- ls - "list directory"
	- rm - "remove file"
	- cp - "copy file"
	- mv - "move file"
	- logout - obvious
	- mail - "send and read your mail"
	- Newsreaders
		- rn, xrn, trn	
		- you should read the following groups
			- ut.cdf.csc270h 
			- ut.cdf.announce 
			- ut.cdf.general
	- Editors
		- vi, emacs, pico, nedit
	- cat - "print file to screen"
		- example: "cat /etc/motd" - prints message-of-the-day
	- more - same as cat but lets you page through the output
	- the Unix file system
		- directories and subdirectories
		- "tree" structure
	- mkdir, rmdir - "make and remove directories"
	- cd - "change directory"
	- pwd - "path of the current working directory"
	- ~hsc/classes/270/examples
		- the directory with all class examples
	- chmod ugo+/-rwx  - "change permissions on a file"
		- Example: chmod go-rwx mycode.c
			- removes read/write/execute permissions for all
			  but the file owner
	- commands can have argument flags - specified by a "-"
		- Example: ls -l directory
	- piping
		- can pipe the output of a command to another command
		  or to a file
		- !, Ex: "ls -l | more", "cat filename | more"
		- >, Ex: "ls -l > listing"
		- <, Ex: "myexecutable < datain > dataout"
		- >&, Ex: "gcc mycode.c >& errors"

IV. Why learn C?
	- a large amount of historical code written in C
	- still the best systems programming language
		- Unix written in C
	- learn the structured/procedural programming style
	- help understand how a computer works (like assembly)

V. C vs Java
	- C is more dangerous - not type checked
	- C has much of the same syntax
		- if, for, while, switch, primitive data types
	- no classes, no exceptions
	- difficult I/O
	- C has simple types
		- characters, integers, floating points
		- pointers, arrays, structures, unions
	SEE EXAMPLES hello_world.c, hello_world2.c, hello_world3.c, sums.c

VI. C program structure
	1) includes
	2) defines
	3) global variables - not recommended
	4) function prototypes
	5) int main(void) 
           {
           }
	6) helper functions

VII. C procedure structure
	return-type function-name(parameter list)
        {
	  variable declarations

	  code
        }

VIII. C compiler
	- gcc - the compiler
	- a.out - unless specified, this is the default executable which
	  is output by the compiler
	- gcc -ansi -Wall -pedantic -g -o outfile infile.c
		- these are useful flags to gcc
	- gdb - a C debugger, must have compiled with the -g flag

IX. C contol flow is the same as Java
	- if, while, do-while, switch-case, for, continue, break commands
	  all work the same in C as in Java

X. Most relational and logical operators are same in C as in Java
	- >, >=, <, <=, ==, !=
	- ||, &&, !

XI. Basic C data types
	- similar to primitive Java types, but C types only state the
	  size of the data, not its intended use
		- char = 1 byte
		- short = 2 bytes
		- int = 4 bytes
	- a C data type example
		int x = 260;
		char c = 150;
		c = (char)x;
		What is the value of c?
	- floating point numbers are the same as in Java
		- float = 4 byte IEEE floating point
		- double = 8 byte IEEE floating point
	- no boolean type in C
		- in C, 0 = false, not 0 = true
		- can use #defines for true/false
			#define true 1
			#define false 0
		- can cause problems for beginners
			- example: int bool = 5;
				   if (bool)  vs. if (bool == true)

XII. arrays
	- a contiguous sequence of memory
	- declared, initialized, and indexed as in Java
		int a[10];  - indexed from 0 to 9
		int b[10][100];
		int c[5] = {1, 2, 3, 4, 5};
		c[0] = 1, c[3] = 4, etc.

XIII. strings
	- no separate datatype for strings
	- a string is just an array of characters with 
	  the terminating character '\0'
	- must leave space for terminating character!!!
	- strings have a special initialization
		char text[STRING_LENGTH];
		char words[6] = "Hello";
	 	char words[6] = {'H', 'e', 'l', 'l', 'o', '\0'};
	SEE EXAMPLE: capitalize.c

	#include <string.h>
		- contains useful string functions like
		  strlen, strcmp, strcpy, strcat
	SEE EXAMPLE: concat.c

XIV. Magic numbers
	- a numerical constant buried in the code
	- poor style
	- use #defines instead, NO MAGIC NUMBERS!

XV. Procedures
	- break problem up into small sizes
	- a function/procedure lets us encapsulate some operation
	  so we can use it and ignore its implementation
	- we have seen some procedures: printf, scanf, strlen, strcpy
	- procedures should not manipulate global variables - use parameters
	- EXAMPLE: xchoosey.c
	- all C arguments are "call-by-value" 
		- changing value of parameter does not change variable's
		  value in calling procedure
		- example:
			int p(int a)
        		{
		           a = 5;
        		}

        		main()
        		{
        		   int a = 1;
        		   p(a);
        		   printf("%d\n", a);
        		}
	- C scoping rules
		- the "scope" of a variable is the part of code in which
		  in can be accessed
		- the scope of a local variable is just the procedure in
		  which it is defined
		- function parameters are treated the same as local variables

XVI. Comments
	- must be bracketed by /* ... */

XVII. #include
	- tells the compiler to place the contents of the file into your
          code at that location
        - can be #include <system-library.h>
	- or #include "my-library.h"

XVIII. #define
	- #define ITEM   value
	- compiler does a text replacement in the code
	- wherever "ITEM" occurs, it is replaced with "value"