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Notes for Lecture 1 - January 15, 2008
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* Questions for discussion:
** What is programming?
** Why do people write programs?
** Who uses programs?
** Why might one want to learn how to program?
** Why program in C?

* Different views of programs
** A means to solve a particular problem
** A description of the dynamic process of computation.
** An object having many properties of interest
*** Functionality
*** Size
*** Maintainability and understandability
*** Efficiency

* Problem-solving languages
** Examples: basic, perl, python, scheme, ruby
** Primary goal: easy to use -- succinct algorithm description
** Desired behavior easily expressible
** Highly abstract -- characteristics of underlying machine hidden from user
** Intended for small to medium-size tasks
** Programmer and end user are often the same

* Software-construction languages
** Examples: C, C++
** Primary goal: produce production-quality software
** Give user control over the use of memory and hardware devices
** Less abstract -- machine characteristics reflected in language
** Intended for large tasks as well as small
** Can interface to operating system and other software components
** Portability is major concern
** End user is different from programmer

* Network languages
** Examples: Java, C#
** Primary goal: portability, machine-independence, safety and security

* Differences between levels of languages
** C/C++ programs closer to hardware
   They have better control over underlying hardware, memory, and
   operating system functions.
** C/C++ application layer sits just above hardware and OS.
** Problem-solving and network languages hide real machine and OS
   They implement a virtual machine model that is "nicer" than the one
   provided by real hardware and real systems.  The cost is reduced
   efficiency and the inability to access certain hardware features.
** Runtime layer sits between hardware and program in prob. solving lang.

* Some steps in the software development process
** Goals and requirements
** Specification
** Implementation
** Testing

* Hex example
** Description of Hex  (see http://en.wikipedia.org/wiki/Hex_(board_game) )

** Goals and requirements
*** Represent and display puzzle board
*** Assist user in playing game
**** How does user interact with program?
**** How is the data entered?
*** Computer play -- strategy

** Specification
*** Drive by goals and requirements
*** Must spell out desired behavior and user interface

** Implementation
*** Driven by specification
*** Program structure should reflect problem structure
*** Principle of locality

** Testing
*** Critical part of software development
*** Test suite is set of test cases designed to exercise all parts of program
*** Pay special attention to extreme cases

* C programming environment

** File types
*** Source files: .c and .h
**** .h files is header (interface) file for a module
**** .c file is code (implementation) file for a module
**** Object files .o -- machine-code form on a module
**** Precompiled libraries are collections of .o files

** Steps to build an executable file
*** Compiler (gcc -c) produces .o file from .c and .h files.
*** Linker (gcc without "-c") produces executable from .o files and libraries

** Example:
*** gcc -c -o hello.o hello.c
Generates "hello" from "hello.c"
*** gcc -o hello hello.o
Generates "hello" from hello.o and libraries that are searched automatically