cc111 lec#6 : flow charts 1 flow charts reference :understanding computers chapter 13

CC111 Lec#6 : Flow Charts 1

Flow Charts

Reference :Understanding ComputersChapter 13


DefinitionsDefinitionsDefinitionsDefinitions

FlowchartFlowchart:: is a diagrammatic representation that

illustrates the sequence of operations to be performed

to get the solution of a problem.


Standard Symbols UsedStandard Symbols UsedStandard Symbols UsedStandard Symbols Used

A1

Off-page Connector

?Yes

No

Condition

CalculateVariables

Process Rectangle

A

On-Page Connector

PrintPrintResultsResults

Input/OutputStart Or Stop Process

Start


How to Write a Program?How to Write a Program?How to Write a Program?How to Write a Program?

1.Start

2.Define Problem to Solve

3.Think of an Algorithm

4.Think of a Technique for the Solution

5.Write Solution on a Piece of Paper

6.If not Finished Repeat Steps 4 and 5

7.Write Code and Program

8.Debug and Test

9.If not Finished Repeat Steps 7 and 8

10.Stop


How to Write a Program ?(flowchart)How to Write a Program ?(flowchart)How to Write a Program ?(flowchart)How to Write a Program ?(flowchart)

Define Problem to Solve

Stop

Think of an Algorithm (Technique for the solution)

Idea!!!!

Write it down on a piece of paper(before you forget it!!!)

Write Code and Program

Job Done?

Debug and Test

Job Done?

Start

Think of a Technique for the solution

No

Yes

YesNo


DefinitionsDefinitions

An Algorithm

Is a complete step-by-step procedure for solving a

problem or accomplishing a task.

( Where the algorithm is represented by drawing “Flowcharts” )

A computer program makes use of algorithms. A computer program makes use of algorithms.


Basic Flow Chart Operations

1.1. Simple SequenceSimple Sequence2.2. Selection PatternSelection Pattern3.3. Loop PatternLoop Pattern

All computer instructions are based on four basic processing patterns:


1.Simple Sequence

Logic involves executing instructions one statement after another, in the order presented by the program.

This is the simplest and most-used pattern. The computer assumes that all instructions are to be

executed in this order unless the program presents other instructions.


Read Names

Compare with Criteria

Print Eligible Names

Basic Operations of Flow Charts (Simple Sequence)


2. Selection Pattern


Honour Student?

List underStudent Loan

Yes

List underScholarships

No

Basic Operations of Flow Charts (Selection Pattern)


3. Loop Pattern

Directs the computer to loop back to a previous statement in the program, repeating the same sequence over again, usually with new data.

By looping, the programmer avoids having to repeat the same set of instructions over and over


More Names?

No

Yes

Compare with Criteria

Print Eligible Names

Basic Operations of Flow Charts (Loop Pattern)


Flowcharts play a vital role in the programming of a problem and are quite helpful in understanding the logic of complicated and lengthy problems.

Once the flowchart is drawn, it becomes easy to write the program in any high level language.

Often we see how flowcharts are helpful in explaining the program to others.

Hence, it is correct to say that a flowchart is a must for the better documentation of a complex program.

Uses of Flow Charts


Flow Charts document processes and interrelationships of

process steps Flow Charts identify actual and ideal paths where any product

or process flows Flow Charts are used to identify problems and potential

improvements Flow Charts can be completed on entire processes

assemblies with all components, one person or component

through a process, combinations of people and machines,

transactions following forms or other documents, etc.

Uses of Flow Charts…….


Communication: Flowcharts are better way of communicating the logic of a system to all concerned.

Effective Analysis: With the help of flowchart, problem can be analysed in more effective way.

Proper Documentation: Program flowcharts serve as a good program documentation, which is needed for various purposes.

Advantages of Flow Charts


Efficient Coding: The flowcharts act as a guide or blueprint during the systems analysis and program development phase.

Proper Debugging: The flowchart helps in debugging process.

Efficient Program Maintenance: The maintenance of operating program becomes easy with the help of flowchart. It helps the programmer to put efforts more efficiently on that part.

Advantages of Flow Charts….


Complex Logic: Sometimes, the program logic is quite complicated. In that case, flowchart becomes complex and clumsy.

Alterations and Modifications: If alterations are required the flowchart may require re-drawing completely.

Reproduction: As the flowchart symbols cannot be typed, reproduction of flowchart becomes a problem.

The Essentials of what Is Done can easily be lost in the technical details of how it is done.

Disadvantages of Flow Charts


A certain Company gives each of its sales people $1,000 at the beginning of each month to cover travel, lodging, and food expenses.

At the end of the month, a salesperson must total his/her expense receipts. If the amount is less than $1,000 then the difference must be returned to the company.

Case Study - 1Case Study - 1


Here is an algorithm for figuring how much Here is an algorithm for figuring how much money, if any, must be returned:money, if any, must be returned:

1-Total the expense receipts for the month.1-Total the expense receipts for the month.2. Subtract the amount of the expense receipts from 2. Subtract the amount of the expense receipts from 1,000.1,000.3. 3. If the remainder is more than 0, return that amount the remainder is more than 0, return that amount to the company.to the company.

Case Study – 1 (Solution)Case Study – 1 (Solution)


Stop

Subtract ExpensesR <= 1000-E

E<1000?

Start

No

Yes

Input Expenses E

Print You Owe $0Print

You Owe $R

Case Study – 1 (Flow Chart)


What would be the amount to return to the company in this case?

Assume the Employee has Spent$1250

Case Study – 1 (Solution 1)


Stop

Subtract ExpensesR <= 1000-E

E<1000?

Start

No

Yes

Input Expenses


You Owe $R

E=$1250


R= $0


What would be the amount to return to the company in this case?

Now Assume the Employee has Spent $950



Stop

Subtract ExpensesR = 1000-E

E<1000?

Start

No

Yes

Input Expenses


You Owe $R


R= $50


Basic Guidelines for Flow Charting

In drawing a proper flowchart, all necessary requirements should be listed out in logical order.

The flowchart should be clear, neat and easy to follow. There should not be any room for ambiguity in understanding the flowchart.

The usual direction of the flow of a procedure or system is from left to right or top to bottom


• Only one flow line should come out from a process symbol.

Basic Guidelines for Flow Charting(Cont.)


YY

NN

??<<

==

??>>

Basic Guidelines for Flow Charting (Cont.)

Only one flow line should enter a decision symbol, but two or three flow lines, one for each possible answer, should leave the decision symbol.


StopStopStartStart


Only one flow line is used in conjunction with terminal symbol.


Write within standard symbols briefly. As necessary, you can use the annotation symbol to describe data or computational steps more clearly.

If the flowchart becomes complex, it is better to use connector symbols to reduce the number of flow lines.

Avoid the intersection of flow lines if you want to make it more effective and better way of communication.




• Ensure that the flowchart has a logical start and finish.

• It is useful to test the validity of the flowchart by passing through it with a simple test data


Draw a flowchart to find the sum of first 5 natural

numbers..

Case Study - 2


1010

NN SumSum

00 00

11 11

22 33

33 66

44

55 1515

Sum = 0

Stop

N = 0

N = N + 1

?N = 5

Start

Sum = Sum + N

No

Yes

Print Sum


Draw a flowchart to find the largest of three numbers A,B, and C.

Case Study - 3


Stop

?A > B

Start

No

Read A, B, C

?B > C

No

?A > C

No

Print B Print C Print APrint C

Yes Yes Yes

Case Study - 3


Consider four input cases:Consider four input cases:

4. A = 5 ; B = 3 ; C = 3 4. A = 5 ; B = 3 ; C = 3

1. A = 5 ; B = 7 ; C = 3

2. A = 5 ; B = 6 ; C = 7

3. A = 5 ; B = 3 ; C = 7

Case Study – 3 - (Solutions)Case Study – 3 - (Solutions)


Stop

?A > B

Start

No

Read A, B, C

?B > C

No

?A > C

No


Yes Yes Yes

B = 7B = 7

C = 3C = 3

A = 5A = 5



Stop

?A > B

Start

No

Read A, B, C

?B > C

No

?A > C

No


Yes Yes Yes

B = 6B = 6B = 6B = 6

C = 7C = 7C = 7C = 7

A = 5A = 5A = 5A = 5



Stop

?A > B

Start

No

Read A, B, C

?B > C

No

?A > C

No


Yes Yes Yes

B = 3B = 3B = 3B = 3

C = 7C = 7C = 7C = 7

A = 5A = 5A = 5A = 5

Case Study – 3 (Solution 3)Case Study – 3 (Solution 3)


Stop

?A > B

Start

No

Read A, B, C

?B > C

No

?A > C

No


Yes Yes Yes

B = 3B = 3B = 3B = 3

C = 3C = 3C = 3C = 3

A = 5A = 5A = 5A = 5

Case Study – 3 (Solution 4)Case Study – 3 (Solution 4)


Draw a flowchart for computing factorial N (N!). Where N! = 1 ´ 2 ´ 3 ´ …… N .

Test the program for N = 5

Case Study - 4


2424

ii FactFact

00 11

11 11

22 22

33 66

44

55 120120

Fact = 1

Stop

i = 0

i = i + 1

?i >= N

Start

Fact = Fact * i

No

Yes

Print Fact

Read N

NN

55

Case Study – 4

cc111 lec#6 : flow charts 1 flow charts reference :understanding computers chapter 13

Documents

cc111 lec

flow charts reference

basic flow chart operations

computer program

computer instructions

program job

sequence of operations

algorithm technique