Sem1 plt xp_02

Representing the Logic of Programs with Conditions

©NIIT PLT/Lesson 2/Slide 1 of 33

ObjectivesIn this lesson, you will learn about:

Data and data types

Using operators

Representing decisions in a flowchart



Variables and ConstantsFlowchart to display the sum of two numbers

Start

Stop

Accept theSecond Number

Add the two Numbersand Store the Result

Display the Result

Accept theFirst Number



Variables and Constants (Contd.) The internal memory consists of different locations in

which data is stored

A computer needs to identify the memory locations to be able to retrieve values from or store values in them

The value of a variable changes each time the set of instructions is executed

The values stored in the variables are known as constants



Variables and Constants (Contd.)

10 15 25

nNum1 nNum2 nSum

Variables

Constants



Variables and Constants (Contd.)Flowchart to display the sum of two numbers using variables. Start

Stop

Accept nNum2

nSum = nNum1 + nNum2

Display nSum

Accept nNum1



Just a Minute…Identify the variable and constant data in the following situation:

Each day, the courier service delivers some letters. The number of letters is different each day. Regardless of the number of letters delivered by the courier service, they are paid a carrying charge of $5.

Variable:

Constant:



Just a Minute…Identify the variables and constants from the list given below:

a) Age

b) Address

c) 21

d) “10, Kingsway Camp”

e) “Henri”

f) Name

g) “185”



Data Types Numeric

Numeric variables can contain only numbers

These variables can be used in arithmetic operations

Character

Character variables can contain any combination of letters, numbers, and special characters

These variables cannot be used for calculation



Data Types Declaring Variables

Start

Stop

Accept nNum2

nSum = nNum1 + nNum2

Display nSum

Accept nNum1

numeric nNum1,nNum2, nSum



Data Types Variable Naming Conventions

The first letter of the variable may indicate the data type used

The variable name should clearly describe its purpose

In case of multiple words, the first letter of each word could be capitalized for better readability



Using Operators Operators are tools for some predefined operations

The operators that are used in flowcharts are:

Arithmetic operators

Relational operators

Logical operators



Using Operators Arithmetic operators

Arithmetic operators are used to perform arithmetic calculations

The symbols that represent arithmetic operations are called arithmetic operators (*, /, +, -, %)

Relational operators

Relational operators are used to test the relationship between two variables or the relationship between a variable and a constant

There are six relational operators (=,>,<,!=,>=,<=)



Using Operators Logical operators

Logical operators (AND, OR, NOT) are used to combine expressions containing relational operators

nNum1 = 7 AND nNum2 > 5 nNum1 = 7 OR nNum2 > 5 NOT nNum2 <= 5

Precedence of the execution of logical operators are NOT, AND, and OR.



Just a Minute…Draw a flowchart to accept item name, price, and quantity. You need to calculate value as the product of price and quantity, and display the calculated value and the item name using variables.



Representing Decisions in a Flowchart Many problems require decisions to be made

All decisions may or may not state an action to be taken if the condition is false



Representing Decisions in a FlowchartFlowchart Segment to Compare Two Numbers and Check for Equality

Is nNum1 = nNum2 ?

Yes

No

Display “The numbers are

equal”

Display “The numbers are

not equal”



ExampleAccept two numbers and print the larger of the two numbers.

Start

Accept nNum2

Accept nNum1

numeric nNum1,nNum2

A



Example (Contd.)

A

Is nNum1=nNum2?

Is nNum1>nNum2?

Stop

Display nNum2

Display nNum1

Display “ The numbers are equal”

Yes

Yes

No

No



ExamplePrint the value of nX only if the value of nX is greater than 10 and nX is an even number.

Start

Stop

Display nX

Accept nX

numeric nX

IsnX>10 AND nX%2=0?

No

Yes



ExampleAccept the year and then determine whether the year is a leap year or not. A leap year is one that is divisible by 4, other than a century year, such as 1900. A century year, which is divisible by 400, such as 2000, is also a leap year.

To evaluate the given condition, we can interpret this as:

If year is divisible by 4 AND not divisible by 100 OR divisible by 400, it is a leap year.



Flowchart to Determine the Leap Year

Start

Accept nYear

numeric nYear

A

Display “ Please enter a year”



Flowchart to Determine the Leap Year (Contd.)

A

Is nYear % 4=0 AND (nYear % 100 !=0 OR nYear % 400=0) ?

Stop

Display “This is a leap year”

Display “ This is not a leap year”

No

Yes



ExampleTo decide about the discount percentage on a TV, the sales person needs to check the type of TV. If the TV is Black and White [B], the discount will be 5 percent of the selling price. If the type of TV is colored[C], then he has to verify the size of TV screen. For 14 inches screen, discount is 8 percent of the selling price and for 21 inches screen, the discount is 10 percent of the selling price.



Flowchart to Calculate Discount

Start

Stop

Accept cTypeAccept nScreen

numeric nScreen, nDiscountcharacter cType

IscType=‘B’?

Yes

No

IscType=‘C’?

IsnScreen=21?

IsnScreen=14?

nDiscount=5% of SP

nDiscount=8% of SP

nDiscount=10% of SP

Yes

No No

No

Yes

Yes



Problem Statement 2.P.1Study the given flowchart and answer the following questions.

What will be output when:

a) nNum=7

b) nNum=3

c) nNum=11



Problem Statement 2.P.1(Contd.)

Is nNum>10?

Is nNum>5?

Stop

Display “REJECT”

Display “OK”

Display “ GOOD”Yes

Yes

No

No

Start

Accept nNum

numeric nNum



Problem Statement 2.P.2Study the flowchart and answer the following questions.

What will be the output when:

a) nX=150 and nY=75

b) nX=90 and nY=50

c) nX=40 and nY=80



Problem Statement 2.P.2 (Contd.)

Is nX > nY ?

Is nY > 100 ?

Stop

Display nY

Display “ GOOD”Yes

No

No

Yes

Start

Accept nX

numeric nX, nY

Accept nY

Is nX > 100 ?

Yes

No



Problem Statement 2.P.3Draw a flowchart to accept a number and then find out whether or not the number is divisible by 5.



Problem Statement 2.P.4Draw a flowchart to accept three numbers and display the largest number.



Problem Statement 2.P.5Candidates have to enter their age. The age cannot be negative. If a negative age is entered, an error message has to be displayed, otherwise the age is displayed. Represent the error checking logic for this situation using a flowchart.



SummaryIn this lesson, you learned that: Data can be categorized as a constant or variable

Data types can be:

Numeric

Character

The operators are:

Arithmetic

Relational

Logical



Summary (Contd.) Arithmetic operators are used to perform arithmetic

calculations. The symbols that represents arithmetic operations are called arithmetic operators (*,/,+,-,%).

Relational operators are used to test the relationship between two variables. The symbols that represent relational operations are called relational operators (<,>,=,!=).

Logical operators (AND, OR, NOT) are used to combine expressions containing relational operators.

The decision box is used to apply conditions by asking a question in a flowchart.

Technology

Sem1 plt xp_02