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Chapter 12FLOWCHARTS

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Problem Solving� Can be solved in a series of actions � Problem solving steps:

1. Identify the problem2. Understand the problem3. Identify alternatives (solutions)4. Select the best solution4. Select the best solution5. Prepare a list of steps (instruction)6. Evaluate the solution

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SOLUTIONS

Algorithmic Heuristic

the best alternative solution reached by completing actions in steps – algorithm

cannot be reached through direct set of steps

– require reasoning built on knowledge & experience

– a process of trial & error

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Problem Solving with Computers

Solutioninstructions listed during step 5 of problem solving

– must be followed to produce best results

ResultThe outcome or completed

computer-assisted answer

Program

Computers deal with algorithmic solutions & heuristic solutions (artificial intelligence)

Programset of instructions that make up the solution after they have been

coded into a particular computer language

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Constants & Variables

ConstantAn alphabetical and/or numerical value that

never changes during the processing of all the

instructions in a solution

Variable(identifiers) May

change during processing

Given a name & a location in memory

- Referred to by given name

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Drawing the Flowcharts

� Connect blocks by exiting from one and entering another

� The arrowhead is necessary

FLOWLINESFLOWLINES

� Indicate the start & end of a program

�� StartStarthas one flowline exiting�� ExitExit has one flowline entering

StartStart

ExitExit

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Drawing the Flowcharts (cont.)

� For calculations,…� Has one flowline entering and one

exiting

PROCESSINGPROCESSING

� Indicates input to and output from the computer memory

� Has one entrance & one exitI/OI/O

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Drawing the Flowcharts (cont.)

� Indicates a decision� Has one entrance & two exits� One exit is the action when the

resultant is TRUE & other exit is the action when the resultant is FALSEDecisionDecision

i < 10T F

Display “i is less than 10”

ExitExit

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Problem Solving with Computers

Problem: Display Area of a Circle

Steps to solve the problem:1. Declare & Initialize PI value2. Declare & Initialize Radiusvalue3. Declare & Initialize Areavalue4. Calculate Area5. Display the value of Area

10Drawing the Flowchart & Writing AlgorithmDisplay Area of a Circle

Start

Declare & initializePI, Radius andArea

Algorithm1. Constant PI = 3.1422. Variable Radius = 10

Exit

Calculate Area

Display Area

2. Variable Radius = 103. Variable Area = 0.04. Area = PI x Radius x Radius5. Display Area

11Writing the Algorithms Display Area of a Circle

Algorithm1. Constant PI = 3.1422. Variable Radius = 103. Variable Area = 0.04. Area = PI x Radius x Radius5. Display Area

…

PI = 3.142

…

…5. Display Area …

Radius = 40

…

Area = 0.0

…

314.2314.2

Output at monitor screen

12Drawing the Flowchart & Writing AlgorithmDisplay Area of a Circle

Start

Declare & initialize PI, Radius andArea

Algorithm1. Declare Constant PI=3.142, 2. Variable Radius=0

Get Radius

Exit

Calculate Area

Display Area

2. Variable Radius=03. Variable Area=0.04. Get Radius5. Area = PI x Radius x Radius6. Display Area

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PROGRAM STRUCTUREPROGRAM STRUCTUREPROGRAM STRUCTUREPROGRAM STRUCTURE

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Program Structure� Use FOUR logic structures to ensure the solution flows

smoothly from one instruction to the next, rather than jumping between points1. Sequential structure executes instructions one after another in a

sequence2. Decision structure branches to execute one of the possible sets of

instructionsinstructions3. Loop structure executes a set of instructions many times4. Case structure executes a set of instructions out of several sets

� Efficient by providing smooth transformation of data into information besides eliminating the rewriting of identical processes

� Techniques to improve program readability: the 4 logic structure, proper naming of variables, internal documentation and proper indentation

15Figure 1: Sequential Logic Structure

16Figure 2:Decision Logic Structure

17Figure 3:Loop Logic Structure

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Figure 4: Case Logic Structure

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Problem Solving with Computers (e.g.)

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Draw a flowchart to calculate bonus for an employee based on the following table:

Annual Hours Worked Bonus

Less than 2000 hours RM 500Less than 2000 hours RM 500

Between 2000 and 2499 hours RM 500 + 1 month salary

More than 2500 hours RM500 + 2 months salary