Programming Fundamental All Chapter

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DDPC 1573-PROGRAMMINGFUNDAMENTAL

Main ReferenceHanly and Koffman, Problem Solving and

Program Design in C, Fifth Edition, AddisonWesley

ReferenceJoyce Farrell Thomson, Programming Logic

and Design, Fifth Edition

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Chapter 1: Overview of Computers andProgramming

ObjectivesUnderstand computer components and operationsLearn about the steps involved in the programming process

Learn about the data hierarchy and file inputUse flowchart symbols and pseudocode statementsUse and name variablesUse a sentinel, or dummy value, to end a programManage large flowcharts

Assign values to variablesRecognize the proper format of assignment statementsDescribe data typesUnderstand the evolution of programming techniques

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Chapter 1: Computer Components and Operations

2 major components of computer system:HardwareSoftware

Hardware : equipment, or devicesSoftware : programs that contain instructions for thecomputer4 major operations in a computer:

InputProcessingOutputStorage

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Input devices : allow data to enter the computerMouse, keyboard, scanner

Processing : working on the dataOrganizing dataChecking data for accuracyMathematical or other manipulations on data

Central Processing Unit (CPU) : hardware that performsthe tasks

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Output devices : provide data to the userPrinter, monitor, speakers

Programming language : special language containinginstructions for the computer

Visual Basic, Java, C#, C++, COBOLSyntax : rules governing word usage and punctuation inthe language

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Machine language : controls the computer s on/offcircuitryCompiler or interpreter : software that translatesprogramming languages to machine languageProgram must be free of syntax errors to be run, orexecuted , on a computerTo function properly, the logic must be correct

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What is wrong with this logic for making a cake?StirAdd two eggsBake at 350 degrees for 45 minutesAdd three cups of flour

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Logic errors , or semantic errors , are more difficult tolocate than syntax errorsLogic for multiplying a number by 2 (includes input,processing, and output statements)

Get input number.Compute calculated answer as

inputNumber times 2.Print calculatedAnswer.

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2 storage categories:- internal

- external

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- Internal storage :Main memory, random access memory (RAM)Located inside the computer systemVolatile : contents are lost when power goes down

External storage :Persistent : contents are relatively permanent

Floppy drive, hard drive, flash media, magnetic tapeLocated outside the computer systemNon-volatile : contents remain eventhough power goesdown

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Chapter 1: Steps Involved in the ProgrammingProcess

6 programming phases:Understand the problemPlan the logic

Code the programUse software to translate the program to machinelanguageTest the program

Put the program into production

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Understanding the Problem May be the most difficult phaseUsers may not be able to articulate their needs well

User needs may be changing frequentlyProgrammers may have to learn the user s functional jobtasksFailure to understand the problem is the major cause of

most project failures

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Planning the Logic Plan the steps that the program will takeUse tools such as flowcharts and pseudocode

Flowchart : a pictorial representation of the logic stepsPseudocode : Natural language representation of the logicWalk through the logic before coding by desk-checking the logic

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Coding the Program Select the programming language

Some languages more efficient for certain tasks

All languages handle input, arithmetic processing,output, other standard functionsLogic can be executed in any number of languages

Write the instructionsPlanning generally more difficult than coding

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Using Software to Translate the Program into MachineLanguage Programmers write instructions in high-level languages

that resemble a natural languageCompilers or interpreters change the programs into alow-level machine language that can be executedSyntax errors are identified by the compiler or

interpreter

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Creating an executable program

Using Software to Translate the Program into Machine Language

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Testing the Program Execute it with sample data and check resultsIdentify logic errors and correct them

Choose test data carefully to exercise all branches ofthe logic

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Putting the Program into Production Might mean simply running the program onceProcess might take months if program is used on

regular basis or is part of larger developmentTrain data-entry people and usersChange existing data

Conversion : entire set of actions organization must

take to switch over to new program(s)

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1 Planning

2 AnalysisIdentify data objectsGoal to model propertiesDetermine Input / Output dataConstraints on the problem

3 Design

Decompose into smaller problemsTop-down design (divide andconquer)Develop algorithm (Desk check)

4 ImplementationWriting the algorithm

5 TestingVerify the program meets

requirementsSystem and Unit test

6 MaintainingMaintain the system

Software Development Method

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Chapter 1: Interactive Input

Prompt: message displayed on a monitor Asks the user for a response

Command prompt: location to type entries to

communicate with the operating systemGraphical User Interface (GUI): allows users tointeract with a program in a graphical environment

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A prompt, response, and output in a command line environment

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A prompt, response, and output in a GUI environment

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Chapter 1: Data Hierarchy and File Input

Data hierarchy : ordering of data types by sizeCharacter : single symbol

A, 7, $

Field : group of characters forming a single data itemSmith

Record : a group of related fieldsCustomer record containing name and addressfields

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File : a group of related recordsCustomer file, containing all customer records

Database : collection of related files, called tables,that serve the information needs of theorganization

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The data hierarchy

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The EMPLOYEE file represented as a stack of index cards

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Chapter 1: Flowchart Symbols and PseudocodeStatements

Flowchart : pictorial representation of the logicPseudocode : English-like representation of the logic

Example:

startget inputNumbercompute calculatedAnswer as

inputNumber times 2print calculatedAnswer

stop

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Input symbol

Processing symbol

Output symbol

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Flowlines :Connect the stepsShow the sequence of statements

Have arrows to show the direction

Terminal symbol (start/stop symbol):Shows the start and end points of the statementsLozenge shape

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Flowchart and pseudocode of program that doubles a number

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Inefficient pseudocode for program that doubles 10,000 numbers

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Flowchart of infinite number-doubling program

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Chapter 1: Name Variables, Assign Values toVariables

Variable : a memory location whose contents can vary;also called an identifierEach programming language has its own rules for namingidentifiers, including:

Legal charactersMaximum lengthUse of upper- or lowercase

Variable name must be a single word, but can be formedfrom several wordsrate, interestRate, interest_rate

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Chapter 1: Name Variables, Assign Values toVariables

Choose meaningful names for variablesImproves the readability and maintainability of code

Suitability of suggested variable names for an employee s last name


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Chapter 1: Ending a Program by Using SentinelValues

Infinite loop : a sequence of statements that repeatsforever with no escape

Avoid infinite loops by testing for a predetermined valuethat means stop processing

Decision : testing a valueFlowchart decision symbol : a diamond shape with two

flowlines, one for Yes and one for No



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Chapter 1: Sentinel, or Dummy Value to End AProgram

Sentinel value (or dummy value )Does not represent real dataSignal to stopCan be used with input from files or from users

End-of-file (EOF ) marker :Code stored in the file that marks the end of the data

Usually used instead of a sentinel value for file input


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Chapter 1: Sentinel, or Dummy Value to End AProgram

Flowchart using eof38DDC1023 PROGRAMMING METHODOLOGY

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Chapter 1: Manage Large Flowcharts

Flowchart connector symbol :Marks a logic transfer to another location in theflowchart

Transfer location can be on the same page or onanother pageOn-page symbol : a circle with a number or letter toidentify the matching transfer locationOff-page symbol : a square with a pointed bottom,containing page number and a number of letter toidentify the matching transfer location



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Chapter 1: Data Types, the Evolution ofProgramming Techniques

Some programming languages implement several numericdata types, such as:

Integer : whole numbers only

Floating-point : fractional numeric values with decimalpointsCharacter or string data is represented as charactersenclosed in quotation marks

x, color Data types must be used appropriately


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Chapter 1: Data Types, the Evolution ofProgramming Techniques

Some examples of legal and illegal assignments42DDC1023 PROGRAMMING METHODOLOGY


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Chapter 1: Summary

Data hierarchyCharacterFieldRecordFile

Database

Software Development MethodPlanning

AnalysisDesignImplementationTestingMaintaining


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Chapter 1: Summary

Flowchart: pictorial representation of program logic

Variables: named memory locations that contain valuesTesting a value involves making a decision

Assignment statements: store a value into a variable Assignment operator: the equal (=) sign in most

languages2 major data types:textnumeric

Procedural programming:focuses on actions performed on data

Object-oriented programming:focuses on representing and manipulating objects


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Chapter 2: Understanding Structure

Objectives Learn about the features of unstructured spaghetticodeUnderstand the three basic structures:

sequenceselectionloop

Use a priming read Appreciate the need for structure

Recognize structureLearn about 3 special structures: case , do-while ,and do-until


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Chapter 2: Features of UnstructuredSpaghetti Code

Spaghetti code : logically snarled program statementsCan be the result of poor program design

Spaghetti code programs often work, but are difficult to

read and maintainConvoluted logic usually requires more code


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Example: College Admissions Admit students who score >= 90 on admissions test ifupper 75 percent of high-school graduating class

Admit students who score >= 80 on test if upper 50percent of high-school graduating class Admit students who score >= 70 on admission test ifupper 25 percent of high-school graduating class


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Chapter 2: Three Basic Structures: Sequence,Selection and Loop

Structure : basic unit of programming logic Any program can be constructed from only 3 basic typesof structures

SequencePerform actions in orderNo branching or skipping any task

Selection (decision) Ask a question, take one of 2 actionsDual-alternative or single-alternative

LoopRepeat actions based on answer to a question



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Selection structure

Selection structure


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Dual-alternative if : contains 2 alternatives

if someCondition is true thendo oneProcess

else

do theOtherProcess

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Single-alternative if : contains 1 alternative

Single-alternative selection structure


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Loop structureRepeats a set of actions based on the answer to aquestion

Also called repetition or iterationQuestion is asked first in the most common form ofloop

Loop structure

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Loop structure

while testCondition continues to be true

do someProcess

while quantityInInventory remains low

continue to orderItems

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All logic problems can be solved using only these 3structuresStructures can be combined in an infinite number of ways

Stacking : attaching structures end-to-endEnd-structure statements: indicate the end of a structure

The endif statement ends an if-then-else structureThe endwhile ends a loop structure

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Ch t 2 Th B i St t S
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Structured flowchart and pseudocode

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Any individual task or step in a structure can bereplaced by a structure

Nesting : placing one structure within anotherIndent the nested structure s statements

Block : group of statements that execute as a single

unit

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Chapter 2: Three Basic Structures: Sequence


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Flowchart and pseudocode showing a sequence nested within a selection


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Flowchart and pseudocode for loop within selection within sequence within selection

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Chapter 2: Three Basic Structures: Sequence


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Each structure has 1 entry and 1 exit pointStructures attach to others only at entry or exit points

The 3 structures

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Chapter 2: Reasons for Structure

Provides clarityProfessionalismEfficiency

Ease of maintenanceSupports modularity

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Chapter 2: Reasons for Structure

Any set of instructions can be expressed in structuredformat

Any task to which you can apply rules can be expressedlogically using sequence, selection, loop

It can be difficult to detect whether a flowchart isstructured

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Chapter 2: Recognize Structure

Is this flowchart structured?


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Untangling Example 1, 1st step

Single process like A is part of an unacceptable

structure At least the beginning of a sequence structure

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B begins a selection structure

Sequences never have decisions in themLogic never returns to B

Untangling Example 1, 2nd step

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Chapter 2: Recognize StructurePull up on the flowline from the left side of B

Untangling Example 1, 3rd step

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Next, pull up the flowline on the right side of B

Untangling Example 1, 4th step

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Chapter 2: Recogni e Str ct re


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Pull up the flowline on the left side of D and untangle itfrom the B selection by repeating C


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Chapter 2: Recognize Structure Now pull up the flowline on the right side of D


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Ch t 2 R i St t


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Chapter 2: Recognize StructureBring together the loose ends of D and of B

Finished flowchart and pseudocode for untangling Example 1

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Chapter 2: Three Special Structures: case do while


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Chapter 2: Three Special Structures: case, do-while,and do-until

Many languages allow 3 additional structures:The case structureThe do-while structureThe do-until structure

CASE Structure:Decisions with more than 2 alternativesTests a variable against a series of values and takes

action based on a matchNested if-then-else statements will do what a case structure does


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Using a case structure for multiple alternatives

Flowchart and pseudocode of case structure

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do-while and

do-until loops

Question is asked at the end of the loop structureLoop statements always used at least once

The while loop, which isa pretest loop

Structure of a do-while or do-until loop, which are posttest loops

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do-while : executes as long as the question s answer isYes or Truedo-until : executes as long as the question s answer isNo or False

dowash a dish

until all dishes are washed

dowash a dish

while more dishes remain to be washed

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while loop with question at beginning is called apretest loopdo-while and do-until with question at end arecalled posttest loops

Posttest loop can be replaced with a sequencefollowed by a pretest while loop

pay a bill

while there are more bills to paypay a bill

endwhile

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Flowchart and pseudocode for do-while loop

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Flowchart and pseudocode for sequence followed by while loop

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Chapter 2: Three Special Structures: case do-while


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How can this design be made structured?

Unstructured loop

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Chapter 2: Three Special Structures: case do-while


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Repeat the needed step to enforce structure

Sequence and structured loop that accomplish the same tasks as Figure 2-37


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Chapter 2: Summary


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Chapter 2: Summary

case structure: questions with multiple alternatives

while loop: a pretest loop asks the question first

while loop statements never execute if the answer is No

do-while and do-until loops: posttest loops that askthe question last

do-while and do-until loop statements are alwaysexecuted at least oncePosttest loop can be replaced by a sequence followedby a while loop

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Chapter 3: The Program Planning Process:


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Chapter 3: The Program Planning Process:Documentation and Design

ObjectivesLearn about documentationLearn about the advantages of modularization

Learn how to modularize a programDeclare local and global variables and constantsUnderstand the mainline logic for many proceduralprograms

Create hierarchy charts

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Chapter 3: Learn About Documentation

Documentation All supporting material that goes with a programTwo major categories: for users and for programmers

Usually created by system analysts and/or tech writersMay be printed or electronic (Web or CD)End users : people who use computer programsProgram Documentation

Internal program documentation: comments withincodeExternal program documentation: supportingpaperwork written before programming begins

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Output DocumentationDescribes the results the user can see when a programis completeUsually written firstPlanning done in consultation with the end user

After desired output is known, programmer can planprocesses needed to produce outputMost common types of output:

Printed reportsScreen output

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Designing Printed Reports Printed reports: designed using a print chartCreated using word-processor or design software

Printed reports may contain:Detail lines : display data detailsHeading lines : contain title and column headingsTotal (or summary ) lines : contain statistics or end ofreport indicators

Printed reports may contain only summary information
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Inventory records displayed in a GUIenvironment

Inventory records displayed in arunning program

Designing Screen Output

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Input Documentation Describes what input is available to produce the outputFile description :

Describes data stored in a fileIndicates fields, data types, and lengths

Inventory file description

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Input Documentation Input files organized in different ways

Field may occupy exactly 15 characters for eachrecord

Adding characters to the end of a data field to forceit to a specified size is padding the fieldSome names might be truncated or abbreviated

Fields may be delimitedDelimiter: character that separates fieldsNumeric fields may occupy a specified number ofbytes

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Completing the Documentation Program documentation may contain:

Output designInput descriptionFlowchartsPseudocodeProgram code listing

User documentation may contain:ManualsInstructional materialOperating instructions

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Completing the Documentation User documentation:

Written clearly in plain language

Usually prepared by system analysts and/or techwriters

User documentation usually indicates:How to prepare input

Output distribution and interpretationError message informationRun frequency
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Chapter 3: The Advantages of Modularization

Modularization : breaking a large program into modules Advantages of modularization:

Provides abstraction

Allows multiple programmers to work simultaneously Allows code reuseMakes identifying structures easier

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Modularization Provides AbstractionFocuses on important properties while ignoring non-essential details

Avoids low-level details

Makes complex tasks look simpleHigh-level programming languages allow English-likevocabulary

One statement corresponds to dozens of machineinstructions

Modules provide another way to achieve abstraction


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Modularization Allows Multiple Programmers to Workon a Problem Commercial programs rarely written by a singleprogrammer

Development time is significantly reducedLarge programming projects can be divided into modulesModules can be written by different programmers orprogramming teams

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Modularization Allows You to Reuse Your WorkSubroutines that are useful should be used more thanonce in a program

Example: routine that checks the current dateInstructions placed in their own module are easy to portto other applicationsReusability : the ability to use modules in a variety ofapplicationsReliability : assurance that a module has been testedand proven to function correctlyReliable software saves times and money

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Chapter 3: How to Modularize A Program

Most programs contain a main programContains the mainline logic

Accesses other modules or subroutines

Rules for naming modules different for everyprogramming language

For this text:Must be one word

Should be meaningfulFollowed by a set of parenthesesCorresponds to module naming in Java, C++, C#


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Sample logic Logic from left figure using a method

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Logic using two methods

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Method is encapsulated in another method if it iscontained in another methodKnowing when to break a module into its ownsubroutines or submodules is an artBest practice: place together statements that contributeto one specific taskFunctional cohesion : extent to which the statementscontribute to the same task

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Chapter 3: Declare Local and Global Variables and


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Chapter 3: Declare Local and Global Variables andConstants

Arguments: data items required by a methodReturning a value: data sent back by a methodMethod must include:

Header: includes method identifier, other identifyinginformationBody: contains all statements in the methodReturn statement: marks the end of the method

Returns control to the calling methodData items are visible only within the method in whichthey are declared

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Constants

Program that prints a bill using main program that calls nameAndAddress() method

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Variables and constants are in scope only within methodin which they are declared

Variables and constants are local to the method

Global variables and constants are known to the entireprogramVariables and constants declared outside any method aredeclared at the program level

Reasons to declare variables globally:Needed in many methods throughout a programDeclare class s data fields at class level

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Declaring global variables and constants: violatesencapsulationDeclaring variables and constants within methods:methods are portableWhen two or more methods require access to same data,pass the data between methods

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Constants

Program that prints a bill with some constants declared globally

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Chapter 3: Mainline Logic for Many Procedural


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p : g yPrograms

Mainline logic of most procedural programs followssame general structure:

Housekeeping tasks

Variable and constant declarationsOpening filesMain loop tasks

Processes that must occur for every data record

End-of-job tasksPrint footer linesClose open files

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Chapter 3: Mainline Logic for Many ProceduralPrograms


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Programs

Flowchart and pseudocode of mainline logic for a typical procedural program

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Chapter 3: Mainline Logic for Many Procedural


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p g yPrograms

Sample payroll report

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Chapter 3: Mainline Logic for Many ProceduralPrograms


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Programs

Logic for payroll report

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Chapter 3: Create Hierarchy Charts


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Hierarchy chart :Illustrates modules relationships Tells which routines call which other routinesDoes not tell when or why the modules are called

Hierarchy chart program

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Chapter 3: Create Hierarchy Charts


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An organizational hierarchy chart


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Chapter 3: Summary


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Documentation: all supporting material for a programOutput documentation: includes report designsFile description: details data types and lengths of eachfield of data in the fileUser documentation: manuals and instructional materials,and operating instructionsModules: smaller, reasonable units of code that providereusability

Subroutines, procedures, functions, methodsModularization:

Provides abstraction Allows multiple programmers to work on a problemMakes it easy to reuse work and identify structures

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Chapter 3: Summary


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Modules can call other modulesFlowchart symbol is a rectangle with a bar across thetop

Variable declarations define the name and type of thedata to be storedHierarchy chart illustrates modules relationships Common structure for procedural programs:

Housekeeping tasksMain loop

End-of-job tasksHierarchy chart illustrates modules relationships

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Chapter 4: Making Decision


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Objectives Evaluate Boolean expressions to make comparisonsUse the relational comparison operatorsLearn about AND logicLearn about OR logicMake selections within rangesLearn about precedence when combining AND and OR

selectionsLearn more about the case structureUse a decision table

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Chapter 4: Evaluating Boolean Expressions to Make


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Comparisons

Dual-alternative (or binary ) selection structure: Provides an action for each of 2 possible outcomes

The dual-alternative selection structure

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Comparisons

Single-alternative (or unary ) selection structure Action is provided for only 1 outcome

The single-alternative selection structure


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Chapter 4: Evaluating Boolean Expressions to MakeComparisons


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Comparisons

Pseudocode for payroll program with dental insurance determination

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Comparisons

Boolean expressionRepresents only one of 2 statesEvaluates to true or false

Every decision in a computer program involvesevaluating a Boolean expressionComputer circuitry consists of two-state on-off switches

Represented by 1 or 0

Every computer decision yields a true-false result

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Chapter 4: Relational Comparison Operators


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For any 2 values, 3 types of comparisons:2 values are equal1st value greater than the 2nd value

1st value less than the 2nd value

Relational comparison operatorsExpress Boolean tests

Different languages use different symbols


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Using a negative comparison

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Using the positive equivalent of the negative comparison in Figure 4-5

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Relational comparisons

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Chapter 4: AND Logic OR Logic


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Understanding AND LogicCompound condition

Asks multiple questions before an outcome isdetermined

AND decision Requires that both of 2 tests evaluate to TrueRequires a nested decision (nested if )

Using nested if statements

Second selection structure is contained entirelywithin 1 side of 1st structure

else clause paired with last if

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Flowchart and pseudocode for selection process in revised bonus-determiningprogram

Understanding AND Logic

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Nesting AND Decisions for Efficiency When nesting decisions, either selection can come firstPerformance time can be improved by asking questionsin the proper orderIn an AND decision, first ask the question that is lesslikely to be true

Eliminates as many instances of the 2nd decision aspossibleSpeeds up processing time

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Understanding OR Logic When you want to take action when 1 or the other of 2conditions is true

Example:Salespeople get bonus when they have achieved oneof two goals:

Sell at least five itemsSell at least $2,000 in merchandise

itemsSold >= ITEMS_MIN ?If true, assign $300 bonus

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Chapter 4 : AND Logic OR Logic


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Writing OR Decisions for Efficiency May ask either question first

Both produce the same output, but vary widely innumber of questions asked

If first question is true, no need to ask second

In an OR decision first ask the question that is more

likely to be trueEliminates as many repetitions as possible ofsecond decision

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Chapter 4: Precedence When Combining AND and OR


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Selections

Combining Decisions in an AND SelectionConditional AND operator allows you to ask 2 or morequestions in a single comparisonEach Boolean expression must be true for entireexpression to evaluate to trueTruth tables describe the truth of an entire expressionbased on the truth of its partsShort-circuit evaluation: expression evaluated only asfar as necessary to determine truth

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Chapter 4: Precedence When Combining AND and OR S l i


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Selections

Combining Decisions in an OR SelectionConditional OR operator allows you to ask 2 or morequestions in a single comparisonOnly one Boolean expression in an OR selection mustbe true to produce a result of trueQuestion placed first will be asked first, so considerefficiencyComputer can ask only one question at a time

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Chapter 4: Precedence When Combining AND and OR l


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Selections

Truth table for the AND operator

Combining Decisions in an AND Selection

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Selections

Truth table for the OR operator

Combining Decisions in an OR Selection


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Selections

Using an OR operator and the logic behind it

Combining Decisions in an OR Selection

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Chapter 4: Case Structure


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Provides a series of alternatives based on the value ofa single variable

Replaces a series of chained if-else statements

Makes code easier to read

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Chapter 4: Case Structure


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Flowchart and pseudocode that determines base price for house based onmodel number using the case structure

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Chapter 4: Decision Table


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Managing multiple possible outcomes of multiple decisions can be difficult

Decision table : four-part problem-analysis tool

ConditionsPossible combinations of Boolean values for eachconditionPossible actions based on the conditions

Specific actions that correspond to each Booleanvalue of each condition

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Sample residence hall assignments report

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Rules for assigning residence hallsStudents under age 21 who request a hall with quietstudy hours: Addams HallStudents under age 21 who do not request a hallwith quiet study hours: Grant HallStudents age 21 and over who request a hall withquiet study hours: Lincoln HallStudents age 21 and over who do not request a hallwith quiet study hours: Lincoln Hall

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To create a decision table:List all possible conditionsDetermine the possible Boolean value combinationsfor each condition# combinations = 2 (number of conditions)

Conditions and possible values for residence hall determination

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To create a decision table: Add rows to list possible outcome actionsChoose one required outcome for each combination

Completed decision table for residence hall selection

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Program that assigns a student to a residence hall

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Chapter 5: Looping


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Objectives Learn about the advantages of loopingControl loops with counters and sentinel valuesNest loopsUse posttest loopsRecognize the characteristics shared by all loopsLearn about common loop applications

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Chapter 5: Advantages of Looping


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Looping makes computer programming efficient andworthwhileWrite one set of instructions to operate on multiple,separate sets of dataLoop : structure that repeats actions while somecondition continues

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Chapter 5: Advantages of Looping


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The while loop

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Chapter 5: Control Loops with Counters andSentinel Values


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As long as a Boolean expression remains true, while loop s body executes Must control number of repetitions to avoid an infiniteloop

Repetitions controlled byCounterSentinel value

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Using a Definite while

Loop with a Counter Three actions make a while loop end correctly:

Loop control variable is initializedPrior to entering the loop

Loop control variable is testedIf result is true, loop body entered

Loop control variable must be altered in loop bodywhile expression eventually evaluates to false

Loop control variables altered by:IncrementingDecrementing

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Using a Definite while Loop with a Counter


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DDC1023 PROGRAMMING METHODOLOGY 159 A while loop that prints Hello four times

g while p

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Using a Definite while Loop with a CounterDefinite loop : number of iterations predetermined

Also called counted loopCounter : numeric variable used to count number of

times an event occursLoop control variable may be altered by user inputIndefinite loop : loop iterates until some condition is true

Number of iterations may vary

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Using an Indefinite while Loop with a Sentinel Value Indefinite loop: loop performed a different number oftimes each time the program executes3 crucial steps:

Starting value to control the loop must be providedComparison must be made using the value thatcontrols the loopWithin the loop, value that controls the loop must be

alteredLoop control variable : any variable that determineswhether the loop will continue

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Looping bank balance program

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Typical execution of the looping bank balance program

Using an Indefinite while Loop with a Sentinel Value

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DDC1023 PROGRAMMING METHODOLOGY 164Crucial steps that must occur in every loop

Using anIndefinite while Loop with aSentinel Value

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Chapter 5: Nested Loops


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Nested loops : loops within loopsOuter loop : loop that contains the other loopInner loop : loop that is containedNeeded when values of two (or more) variables repeat

to produce every combination of values

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Flowchart and pseudocode for AnswerSheet program

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Chapter 5: Posttest Loops


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Loop body may never execute in while loop and for loopUse posttest loop when loop body must execute at leastonce

do-until loop do-while loopdo-until loop executes until condition is truedo-while loop executes until condition is false


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Chapter 5: Posttest Loops


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Label production program using a do-until loop

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Chapter 5: The Characteristics Shared by AllLoops


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Every logical problem could be solved using only thewhile loopOther forms are conveniences

while loop

Loop-controlling question placed at beginning of stepsthat repeat

do-until loopLoop-controlling question placed at end of steps that

repeat

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Characteristics of all structured loops:Loop-controlling question must provide entry or exitfrom repeating structureLoop-controlling question provides the only entry to or

exit from the repeating structureExactly one loop-controlling value

Provides only entry to or exit from the loop

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Examples of unstructured loops

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Chapter 5: Common Loop Applications


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Using a loop to accumulate totalsExamples:

Business reports often include totalsTelephone bill provides a total

List of real estate sold and total value

Accumulator : variable that gathers valuesSimilar to a counter

Counter increments by one Accumulator increments by some value

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Accumulate total real estate pricesDeclare numeric variable at beginningInitialize the accumulator to 0Read each transaction s data record

Add its value to accumulator variableRead the next record until eof

Variables exist only for the life of the applicationRun the application a second time, variables occupydifferent memory location

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Month-end real estate sales report

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Flowchart and pseudocode for real estate sales report program

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Using a loop to validate dataWhen prompting a user for data, no guarantee thatdata is valid

Validate data : make sure data falls in acceptable ranges

Example: user enters birth monthIf number less than 1 or greater than 12

Display error message and stop the program Assign default value for the monthReprompt the user for valid input

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Reprompting a user once after an invalid month is entered

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Reprompting a user continuously after an invalid month is entered

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Chapter 5: Summary


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When using a loop, write one set of instructions thatoperates on multiple, separate dataThree steps must occur in every loop:

Initialize loop control variable

Compare variable to some value Alter the variable that controls the loop

Nested loops: loops within loopsNested loops maintain two individual loop controlvariables

Alter each at the appropriate time


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Chapter 6: Overview of C


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Objectives Learn about the C language elements

Apply the variable declarations and data types.Understand Input/output functions printf and scanf .Include preprocessor directives #include and #define Use assignment statement with arithmetic operatorsLearn about the general form of a C program

Apply the formatting numbers in program outputKnow the interactive modeIdentify the common programming errors

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Chapter 6: C Language Elements


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Preprocessordirectives

Main function

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Chapter 6: Variable Declarations and Data Types


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Variables: values stored in variables can changesVariables Declarations:

What kind of information will be stored in eachvariable

How that information will be represented inmemory

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Chapter 6: Variable Declarations and Data Types
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Variable declaration according to its data type.

EXAMPLES:int count,large;

double x, y, z;char first_initial;char ans;
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Chapter 6: Executable Statements

Program in Memory


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Memory(a) Before and (b) After Execution of a Program

Program in Memory

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kms = KMS_PER_MILE * miles;

Assignment Statements

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Chapter 6: Executable StatementsBefore and After Assignment of a variable


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sum = sum + item;

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Input and Output Operations and FunctionsOperationsFunctions#include

C function: printfC function: scanf

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Chapter 6: Executable StatementsFunction (printf)


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scanf("%lf", &miles);

Function (scanf)

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Function (scanf)


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scanf("%c%c%c", &letter_1, &letter_2, &letter_3 );

Function (scanf)

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Chapter 6: General Form of a C program


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Preprocessor directives: #include, #define Any used variable should be declared before the usage.
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Chapter 6: Formatting numbers in programoutput


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Chapter 6: Common Programming Errors


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Syntax ErrorsRun-Time ErrorsUndetected ErrorsLogic Errors


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Chapter 6: Common Programming Errors

Run-time error occurs when theg di t th t t f


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program directs the computer to performan illegal operation (e.g., divide by zero).

temp=0divide by zero


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Chapter 6: Summary

E C h di i d


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Every C program has preprocessor directives and amain function.The main function contains variable declarations andexecutable statements.Variable names must begin with a letter or anunderscore and consist of letters, digits, and underscoresymbols.

A reserved word cannot be used as an identifier.

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Chapter 7: Data Types, Operators and SimpleFunctions in C


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ObjectivesUnderstand the data types Able to write program with arithmetic operatorsLearn about the mixed-type assignment statement

Know how to use the expression with multiple operators

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Chapter 7: Data Types

int


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Range : -32767 ~ + 32767 --- in ANSI C-10500 435 +15 -25 32767

double

charA a z 2 9 * ?

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Chapter 7: Arithmetic Operators


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Execution of Multiple Operators


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Can be expressed as an Evaluation Tree .

area = PI * radius * radius;

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Step by Step Expression Evaluation

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Chapter 7: Arithmetic OperatorsEvaluation Tree


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v = (p2 - p1) / (t2 - t1);

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z - (a + b / 2) + w * -y

Evaluation Tree


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z (a b / 2) w y

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Chapter 7: Writing Mathematical Formulas in C

You may encounter two problems in writing a


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You may encounter two problems in writing amathematical formula in C.First, multiplication often can be implied in a formula bywriting two letters to be multiplied next to each other. InC, you must state the * operator

For example, 2a should be written as 2 * a.Second, when dealing with division we often have:

This should be coded as (a + b) / (c + d).

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Chapter 7: Library functionsFunction Header File Description


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abs( x ) Return the absolute value of x

cos( x ) Return the cosine of angle x

exp( x ) Return the value of e x

pow( x , y ) Return the value of x y

sqrt( x ) Return the squre root of x

For I/O library functions ( printf, scanf )To use them, have to use #include

For Mathematical Functions ( sqrt, pow, sin, cos )To use them, have to use #include


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Chapter 8: Selection Structures: If and SwitchStatement In C

Objectives


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ObjectivesLearn about the control structureUnderstand the conditions

Apply the if statement with compound statements

Use decision steps in algorithmsLearn about the nested if statements and multiplealternative decisionsLearn about the switch Statement


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Chapter 8: Conditions

Relational and Equality Operators


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q y p

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Sample Conditions


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p


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Operator Precedence


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An operator s precedence determines its order of evaluation.

- x y * z

x + y < min + max

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Chapter 8: Conditions Evaluation Tree & Step-by-Step Evaluation


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Short Circuit Evaluation


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Short Circuit Evaluation Stopping evaluation of a logical expression as soon asits value can be determined.

e.g. a && b must be false if a is 0 .

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Writing English Conditions in C

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Comparing Characters

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Complement a logical expression


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Complement a logical expressionwith the symbol !

just change its operator

item == SENT

! (item == SENT)item != SENT! ( a b

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Chapter 8: The if Statement

Syntax


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if (condition) statement ;else statement ;

Ex-1.if (rest_heart_rate > 56 )

printf(keep up your exercise program! \ n); else

printf(Your heart rate is in excellenthealth\ n);

Ex-2.if (x != 0.0)

product = product * x;

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Chapter 8: If Statement with Compound Statements


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if (condition){

true task}

else{false task

}

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Chapter 8: Decision Steps in Algorithms

Select from a choice of actions


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Select from a choice of actionsRefer slide 240 and 241 for the algorithms in makingdecision

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Chapter 8: Nested if Statements and MultipleAlternative Decisions
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An if statement with another if statement as its true task orits false task

Dangling Elseif (x > 0)

if (y > 0)a = a + 1;

elseb = b + 1;

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Nested if Example: Road Sign Decision Process


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Road Sign Decision Process


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Multiple-Alternative Decision


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Chapter 8: Nested if Statements and MultipleAlternative Decisions Multiple-Alternative Decision Example


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Chapter 8: The switch Statement


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When the selection isbased on the value of asingle variable or of asimple expression

(called the controllingexpression).

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Chapter 8: The switch StatementExample of a switch Statement
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Chapter 9: Repetition and Loop Statement in C

Objectives


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Learn about the repetition in programsCount loops and the while statementCompute a sum or a product in a loopUnderstand the for and do-while statementLearn about the conditional loops: counter-controlled,sentinel-controlled and flag-controlledDesign the loop
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Chapter 9: Counting Loops and the while Statement

Counter-controlled loop (or counting loop)


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A loop whose required number of iterations canbe determined before loop execution begins.

The syntax

while (loop repetition condition)statement;

Loop repetition condition: the condition that controlsloop repetition.

Infinite loop: a loop that executes forever

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count_emp = 0; /* no employees processed yetExample


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*/while (count_emp < 7) { /* test value of

count_emp */printf("Hours> ");scanf("%d", &hours);printf("Rate> ");scanf("%lf", &rate);pay = hours * rate;printf("Pay is $%6.2f\n", pay);count_emp = count_emp + 1; /* increment

count_emp */

}printf("\nAll employees processed\n");

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Flowchart for a while Loop

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Chapter 9: Computing a Sum or a Product in a Loop

Loops often accumulate a sum or a product by


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repeating an addition or multiplication operation.

Accumulator A variable used to store a value being computedin increments during the execution of a loop.

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Example


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Compound Assignment Operators


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C provide special assignment operators variable op = expression;

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Chapter 9: The for Statements

Three loop control components with the loop body.


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Initialization of the loop control variable,Test of the loop repetition condition, andChange (update) of the loop control variable.

The for statement in C supplies a designed place foreach of these three components.

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Increment and Decrement OperatorsThe increment (i.e., ++) or decrement (i.e., --)operators are the frequently used operators which takeonly one operand.

for(int i=0; i0; i-- ) {}

Side effect: the value of its operand isincremented/decremented by one .

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Prefix and Postfix Increments

h l f h h h h
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The value of the expression in which the ++/-- operatoris used depends on the position of the operator .

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Chapter 9: The for StatementsExample: Factorial Function


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Inc. and Dec. Other Than 1


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Chapter 9: Conditional Loops: counter-controlled,sentinel-controlled and flag-controlled

I i i i ill b bl


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In many programming situations, you will not be able todetermine the exact number of loop repetitions beforeloop execution begins.

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Chapter 9: Loop Design

Problem-Solving Questions for Loop DesignWhat are the inputs?


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What are the outputs?Is there any repetition?Do I know in advance how many time steps willbe repeated?How do I know how long to keep repeating thesteps?

Sentinel-Controlled Loops

Endfile-Controlled LoopsInfinite Loops on Faulty Data

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Chapter 9: Loop DesignSentinel-Controlled Loops

One way to do this is to instruct the user to enter a unique data value,called a sentinel value , after the last data item.


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Chapter 9: Loop DesignExample of Endfile-Controlled Loops


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Infinite Loops on Faulty Data 70 7


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70 7oDetect faulty data

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Chapter 9: Nested Loops

Consist of an outer loop with one or more inner loops.


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Chapter 9: The do-while Statement

When we know that a loop must execute at least onetime


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time.

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Chapter 9: Summary

Repetition and Loop StatementsCounter Controller Loop


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Counter-Controller LoopSentinel-Controller LoopEndfile-Controller Loop

Input Validation LoopGeneral Conditional Loopwhile for and do-while

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