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# Flowcharts - PowerPoint PPT Presentation

Flowcharts. Lecture 12. Symbol. Terminal Symbol: indicates the starting or stopping pointin the logic. Input/Output Symbol: Represents an input or output process in an algorithm. Process Symbol: Represents any single process in an algorithm. Predefined Process Symbol:. Decision Symbol:

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## Flowcharts

Lecture 12

### Symbol

Terminal Symbol:

indicates the starting or stopping pointin the logic.

Input/Output Symbol:

Represents an input or output process in an algorithm

Process Symbol:

Represents any single process in an algorithm

Predefined Process Symbol:

Decision Symbol:

Represents a decision in the logic involving the comparison

Of two values.

## The three basic control structures

Statemement a

Statemement b

Statemement c

Condition p?

T

F

Statemement a

Statemement b

Condition p?

F

T

Statemement a

### 3. Repetition

Condition p?

F

T

Statemement block

### Example 12.1 Add three numbers

• A program is required to read three numbers, add them together and print their total.

• Defining diagram

Start

Number1

Number2

number3

Print total

Stop

### Example 12.2 Find average temperature

• A program is required to prompt the terminal operator for the maximum and minimum temperature readings on a particular day, accept those readings as integers, and calculate and display to the screen the average temperature, calculated by (maximum temperature + minimum temperature)/2.

• Defining diagram

### Example 12.3 Compute mowing time

• A program is required to read from the screen the lenght and widht of a rectangular house block, and the lenght and width of the rectangular house that has been built on the block. The algorithm should then compute and display the mowing time required to cut the grass around the house, at the rate of two square metres per minute.

• Defining diagram

## Flowchart and the selection control structure

### Simple IF statement

Account_

balance <

\$300?

T

F

Service_charge = \$5

Service_charge = \$2

Student_

attendance =

P/T?

F

T

Increment

part_time_count

### Combined IF statement

Student =

P/T AND

Gender =

F ?

F

T

Increment

Female_part_time_count

T

Record

Code =`A‘ ?

F

F

T

Record

Code =`A‘ ?

Increment

Counter_A

Record

Code =`A‘ ?

F

Increment

Counter_B

T

Increment

Error_counter

Increment

Counter_C

### Example 12.4 Read three characters

• Design an algorithm that will prompt a terminal operator for three characters, accept those characters as input, sort them into ascending sequence and output them to the screen.

• Defining diagram

Case

Of

variable

Value 2

Value 3

Value 4

Value 1

Statement_a

Statement_b

Statement_c

Statement_d

### Flowchart and Array

• Design a program that will prompt for and receive 18 examination scores from a mathematics test, compute the class average, and display all the scores and the class average to the screen.

• Defining diagram

### Control Structures required

• An array to store the exam scores – called ´scores´

• An index to identify each element in the array

• A DO loop to accept the scores

• Another DO loop to display the scores to the screen.

Start

Calculate

average

Display

average

Total_score =

zero

I = 1

I = 1

Stop

Prompt and

get

Scores (I)

Display

Scores (I)

to

Total score

I = I + 1

T

I = I + 1

I <= 18 ?

F

T

I <= 18 ?

F

### Flowchart and Module

Design a solution algorithm that will prompt a terminal operator for three characters, accept those characters as input, sort them into ascending sequence and output them to the screen. The algorithm is to continue to read characters until ´XXX`is entered.

• Defining diagram

Process_three_

characters

Sort_three_

characters

Start

Sort_

Three_

characters

Prompt

For

characters

Outpur

characters

Get

characters

Prompt

For

characters

Characters

NOT = xxx ?

F

Stop

Get

characters

T

Start

T

Char_1 >

Char_2 ?

F

Swap

Char_1,

Char_2

Char_2 >

Char_3 ?

T

F

Swap

Char_2,

Char_3

Char_1 >

Char_2 ?

T

F

Swap

Char_1,

Char_2

Stop

### Assignment: Calculate Employee‘s pay

A program is required by a company to read an employee‘s number, pay rate and the number of hours worked in a week. The program is then to validate the pay rate and the hours worked fields and, if valid, compute the employee‘s weekly pay and print it along with the input data.

### Assignment (cont‘)

Validation: According to the company‘s rules, the maximum hours an emplooye can work per week is 60 hours, and the maximum hourly rate is \$25.00 per hour. If the hours worked field or the hourly rate field is out of range, the input data and an appropriate message is to be printed and the emplooye‘s weekly pay is not to be calculated.

Weekly pay calculation: Weekly pay is calculated as hours worked times pay rate. If more than 35 hours are worked, payment for the overtime hours worked is calculated at time-and half.

• Defining diagram

### Hierarchy chart

Compute_employee_pay

Employee_details

Valid_input_

fields

details

Validate_input_

fields

Calculate_

Employee_pay

Print_employee_

details

Fields

Valid?

Start

Employee_

details

Calculate_

Employee_

pay

More

Recods?

Print_

Employee_

details

Validate_

Input:

fields

Stop

Employee_

details

Start

Hours_

Worked

> 60

Valid_input_

fields = T

Print

Error

message

Pay_rate

> \$ 25

Print

Error

message

Valid_

Input_

Fields = T

Valid_

Input_

Fields = F

Stop