CIS162AB - C

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CIS162AB - C

• Introduction to C
• CIS105 Review
• Juan Marquez
• 01_intro.ppt

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Two-Part Presentation

• Part 1
• CIS105 Review
• Part 2
• Introduction to C
• Compiling Process

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CIS105 Review (part 1)

• Hardware
• Information Processing Cycle
• Software
• Programming Languages Generations
• Software Development Life Cycle

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A Computer is an electronic device consisting of
hardware.

• Input Devices
• Keyboard
• Mouse
• Scanner
• Output Devices
• Console (Display)
• Printer

• Storage Devices
• Hard drive
• Zip Disk
• Flash Disk
• Internally
• Central Processing Unit (CPU)
• CPU Executes Instructions
• Memory (RAM)

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Hardware Model
The hardware configuration is used to support the
Information Processing Cycle.
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Information Processing Cycle
Output from one process can serve as input to
another process.
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What do we need to operate the hardware and
transform data into information?
Software!
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Software Two Major Categories

• Operating System (OS)
• Application Software

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Operating System (OS)

• Software that allocates and monitors computer
  resources including memory allocation, storage,
  and security.
• Various devices are controlled using system
  programs called drivers.
• OS ExamplesWindows, UNIX, DOS, VMS, etc.

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Computer Resources

• As we go through the course, we will want to
  conceptually understand
• Memory allocation
• Storage
• Well cover storage later, but lets look at
  memory now

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Main Memory

• Random Access Memory (RAM).
• Contents are lost when power is turned off.
• Measured in bytes.
• Each byte stores eight bits.
• BIT Binary Digit (0 1)
• Each byte is considered a location.
• Each byte has an address to identify its
  location.
• Application currently running and the data being
  manipulated must be loaded in memory (RAM).
• CPU only gets and stores data in RAM.

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Question

• What is a nibble?
• A nibble is half a byte.
• A byte is 8 bits, and a nibble is 4 bits.

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Memory Locations
Address 1 Address 2 Address 3 Address 4 Address
5 Etc All consecutive
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Memory Allocation
Applications
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Application Software

• Actual software we use to process raw data into
  information.
• Application ExamplesWord, Excel, Powerpoint,
  Access, etc.
• Application software is used in many industries.
• Business Accounting, Sales
• Manufacturing Inventory, Labor
• Education Enrollment, Research
• Personal Budgeting, School

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How is software developed, and in particular, how
is application software developed?
By using a programming language!
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Syntax

• There are several languages to choose from.
• Each language has a set of commands that can be
  used.
• Each language has a set of syntax rules that must
  be followed.
• Syntax determines many things like how commands
  are entered and how each command should end
  (period, semi-colon, etc).

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Programming Categories

• Procedural Programming
• The programmer must specify in the correct
  sequence what to do and how to do it. Emphasis
  is on the procedures for solution.
• Programmer controls the processing for users.
• Procedural techniques are used in all categories.
• Object Oriented Programming
• Programming using predefined classes and/or
  programmer defined classes to build programs.
• Event Programming
• Usually related to GUI programs.
• Program reacts to events, like a user clicking on
  a mouse.
• User has a little more control of the processing,
  because they can decide which text to enter
  first.
• The program ultimately validates the data, so
  maintains some control.

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Generations of Programming Language

• Machine Language (1GL)
• Low-level (2GL)
• High-Level (3GL)
• Query Languages (4GL)
• Natural Languages (5GL)GL Generation Language

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Machine Language (1GL)

• Code is Machine or CPU dependent.
• So it is not portable.
• Very cryptic and difficult to code.
• Sample code
• 1001 1010 0110 0101 1100 0011
• Series of binary digits (bits, 0-1).
• Actual code that can be processed by CPU.

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Low-level (2GL)

• Called Assembly.
• Source code is machine and CPU dependent.
• Still cryptic and difficult to code.
• Sample code
• add P,TL (add price to total)
• add T,TL (add tax to total)
• This code is transformed to machine language by a
  program called an assembler.

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High-level (3GL)

• Languages are ANSI.
• American National Standards Institute
• Machine and CPU independent.
• Code is more English like.
• COBOL code
• Add tax to price giving total. (note period)
• C, C, and Java Code
• total tax price
• Code is transformed to executable machine
  language by using special programs called a
  compiler and linker.

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Compiler and Linker

• Compiler
• Verifies the program is coded with commands it
  recognizes and that the proper syntax was used.
• Creates an object file (machine language).
• Linker
• A program that combines the programs object file
  with object code of standard routines from the
  library.
• Creates the final executable file.

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Procedural Languages

• 1st, 2nd, and 3rd GLs are procedural.
• The programmer must specify in the correct
  sequence what to do and how to do it.
• Instructions are in detail and precise.

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Query Languages (4GL)

• 4GLs are nonprocedural.
• Programmers must only specify what to do.
• The tool figures out how.
• Many report writers fall into this category.
• Focus, Datatrieve, and SQL (Structured Query
  Language)
• There are still syntax rules to follow.
• Sample SQL Code
• Select sum(enrolled) from enrollment where course
  CIS163AA

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Natural Languages (5GL)

• A computer language that incorporates the
  concepts of knowledge-based systems, expert
  systems, inference engines, and natural language
  processing .
• Very loose syntax rules.
• Sample code
• What is the total enrollment in the Java courses?
• Must define enrollment and Java (CIS163AA) for
  the product.
• Some loose definitions include Visual Basic, but
  VB is not a 5GL. It does not meet the definition
  above.

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Programming

• Programming is solving a problem using a
  computer.
• A program is a set of specific instructions for a
  computer to follow.
• It is a complex process and each program takes on
  a life of its own called SDLC.
• Software Development Life Cycle

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SDLC

• Software Development Life Cycle.
• There are various methodologies to develop
  programs, but most follow the same process.
• The actual name for each step in the process may
  vary by vendor.

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SDLC 3 Phases, 8 Steps

• Problem Solving Phase
• Problem Definition
• Algorithm Design
• Implementation Phase
• Build, Test, Install, and Training
• Support Phase
• Maintenance
• Obsolete

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SDLC - Problem Solving Phase

• Problem definition (Analysis of the task)Users
  need a screen to do a Sales Order
  Calculation.(qty, price, tax, freight)
• Algorithm Design (Solution)Desk check with
  common and extreme data.

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Problem Solving Diagrams

• Diagrams are independent of programming
  language.

• Analysis Diagrams / Tools
• Data Flow Diagram (DFD)
• Entity Relationship Diagrams (ERD)
• Functional Descriptions
• Use Case Diagrams (Object-Oriented)

• Design Diagrams / Tools
• Input Output Charts (IPO)
• Flowcharts - detailed logic
• Structure charts modules identified
• Class Diagrams (Object-Oriented)

• We will see examples of these throughout the
  course.

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SDLC Implementation Phase

• Implement or Build (Code the program).
• Test the program using test data.Actual output
  must match expected results.
• Deploy or install.May require data conversion or
  hardware upgrades.
• Training User Documentation.

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SDLC Support Phase

• Maintenance change program as needednew tax
  rates, new freight carrier, etc.zip4, Y2K, new
  area code.
• Obsolete program is discarded due to requiring
  too much effort to corrector new technology (DOS
  to Windows).

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On Your Homework Assignments

• I will provide
• problem definition
• You will
• Design Algorithm
• Build
• Test

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C Introduction (part 2)

• C History (brief)
• Sample Program
• Coding Style
• Some C statements
• Compile, Link, and Execute
• Programming Errors

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History of C

• C was derived from C.
• C was developed by ATT Bell Laboratories in the
  late 70s.
• C was used to write UNIX, which is an Operating
  System (OS).
• C was then used to develop commercial
  applications to run on UNIX.
• Eventually C compilers were developed for other
  OSs.

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Features of C

• C is a high-level language with features of a
  low-level language.
• C can directly manipulate the computers memory
  like an OS (consider UNIX history).
• Can be difficult to understand and use if coded
  cryptic.

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Introduction to C

• C was developed to be a better C (1980s).
• Most C programs compile as C programs, because
  many of the old libraries are still maintained in
  C.
• C has the capability to do object-oriented
  programming (OOP) through the use of classes.
• We will learn how to develop classes in the last
  section of this course.

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Coding Style

• Block layout indent related code.
• Make programs easy to read.
• Use whitespace between commands and sections.
• Open and closing braces on separate lines .
• Each command on a separate line.
• Each statement ends with a semicolon ( ).
• Declare all variables at the top.

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Sample C Program

• //P01 Hello World - Juan Marquez TR 100pm
• include ltiostreamgt
• using namespace std
• void main( )
• cout ltlt Hello World by Juan Marquez \n\n"

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Text files to Machine Language

• C programs are text files .
• In Windows they have a .cpp extension,P01.cpp.
• C programs can be written in any text editor,
  such as Notepad or Wordpad.
• Well be using Microsoft Visual C, which
  includes a text editor.
• Text files must be converted to machine language.
• How?
• By compiling

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Compiling
Text Editor
P01.cpp
WarningsErrors
Compiler
P01.obj
Library iostream
Linker
P01.exe
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Three Categories of Errors

• Syntax Errors and Warnings
• Logic Errors
• Run-time Errors
• Actually are logic errors.

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Syntax Errors Warnings

• Detected by compiler, but corrected programmer.
• Violation of grammar rules.
• Mistyped commands.
• Compiler tells you what the error is,or what it
  thinks it is.
• Compiler tries to tell you where the error
  occurred.
• Warnings
• Passes syntax rules but not normally coded this
  way.
• Programmer should check for possible logic error.

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Logic Errors

• Detected and corrected by programmer.
• Program designed or written incorrectly.
• Output generated does NOT match expected output.
• Simple to very complex.
• Using (multiply) instead of (add)
• Test, test, text and verify results.
• This is where programmers earn their money.

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Run-time Errors

• Usually discovered by user, but corrected by
  programmer.
• Program terminates unexpectedly.
• Error access violation
• Usually based on a logic error.
• Divide by zero
• Users do something programmer didnt expect them
  to do.
• Processing unexpected input, such as entering
  letters instead of numbers.
• Users need to document what they were doing when
  the error occurred to help programmer.

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Summary

• Hardware Components
• Information Processing Cycle
• Software Categories
• Generations of Programming Languages
• Software Develop Life Cycle (SDLC)
• Compiling Process
• Types of Errors