COMPUTER APPLICATIONS Ch: 3 Values and Data...

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COMPUTER APPLICATIONS

Ch: 3 Values and Data types

➢ Syllabus:

Introduction,

Tokens, Constants, Literals,

Data Types

Identifiers

Variables

Punctuators

Data Type Conversions

ACSII codes

➢ Introduction

Data types are the basis of any programming language. Without data type,

programming is not possible.

Java provide you various in-built data type. These in-built data types are

called primitive data types. You can create your own data types in Java

programs by using primitive data types.

➢ Tokens

Tokens are the various Java program elements which are identified by the

compiler. A token is the smallest element of a program that is meaningful to

the compiler. Tokens supported in Java include keywords, variables,

constants, special characters, operations etc.

Different types of tokens are:

• Reserved words or keywords

• Identifiers


• Literals

• Punctuators

• Operators

Note: for more details about tokens open the following link

https://www.youtube.com/watch?v=L17kre7RVtc&feature=youtu.be

➢ Constants

Constants are the fixed values that do not change during the execution of

the program. Constants are also called literals.

Figure:

Java supports various types of constants.

Integer Constants

These are the sequence of digits. There are three types-decimal, octal,

hexadecimal.

• Decimal constants:

Example of some valid decimal constants:

120, 375, -120, 4562

Example of some invalid decimal constants:

(i) 1,20 (ii) 1 60 (iii) 145 A

No space, comma and no alphabet or special character is permitted between

digits.



• Octal constants:

It contains combination of digits from 1 to 7.

Example:

0, 47, 324, 76342

• Hexadecimal constants:

It contains combination of digits from 1 to 9 and alphabets from A to F

Example:

7FA, 2DG, B5A, 89

Real Constants

These are the numbers containing fractional part.

These are also called floating point constants.

Example:

1.236 , -2.45, 39.27, -45.02

Single character Constants

A single character constant contains only single character enclosed in single

quotes.

Example:

‘A’, ‘7’, ‘P’

String Constants

A string constant is sequence of character enclosed in double quotes.

Example:

“Hello”, “Pramod Rajput”, “My favourite subject is Computer”

Special character, blank spaces, digits are allowed in string constants.

Note: for more details about literals open the following link




➢ Literals

Literals is a programming language term, which means that what you type is

what you get.

If you type 4 you will get a 4.

Some special cases of literals are:

Numbers, characters, strings and Boolean literals.

Number Literals

There are several integer literals. For example, 4 is int literal.

You can force a smaller number to long by appending the letter l or L to that

number. For example, 5L is a long integer.

Floating point literals for example 3.14114

You can force a number to the type float by appending the letter f or F to

that number. For example, 5.43F.

Boolean Literals

Boolean literals consist of the keywords, true and false. These keywords can

be used anywhere you need a test.

Character Literals

Character literals are expressed by a single character surrounded by single

quotes.

Example:

‘P’, ‘5’, ‘#’

String Literals

A combination of character is string. String literals consist of a sequence of

characters inside double quotes.

Example:

“My name is Pramod”, “2020” etc.

“” is an empty string.

➢ Data types

A programmer while writing programs has to deal with various type of data.


Primitive or Intrinsic Data types

Primitive data types are in-built data types. Java support eight types of

primitive data types.

These are byte, short, int, long, float, double, char and boolean


• Integer

Integer are whole numbers such as 5, 7, -12,56, -9 etc. No fractional part is

used in integer.

(i) Byte

A byte is a primitive data type that uses eight bits to represents a

number. It is ranging from number -128 to 127

(ii) Integers

Integers are those positive or negative whole numbers whose value

varies from -2147483648 to 2147483647.

The type int is a primitive data type that uses four bytes to represent

whole numbers.

(iii) Short

Short integers are those positive or negative whole numbers whose

value varies from -32768 to 32767.

The type short is a primitive data type that uses two bytes to

represent whole numbers.

(iv) Long

The type long is a primitive data type that uses eight bytes to

represent whole numbers.

A bit is a binary digit that can have value of one or zero. A byte is

group of eight bits.

• Floating Point Constants

Float data type:

Fractional number is floating point number.


Example:

5.0, 12.45, -24.654, 0.321 etc.

We can write floating point number in the following format also:

Standard format:

91360000 ------→ 9.136 x 107

Exponent format:

9.136 x 107 ------→ 9.136E7

In this exponent from left part of E is called mantissa i.e. 9.136

In this exponent from right part of E is called exponent i.e. 7

Double:

Type double is primitive data type.

The type float provides 7 digits of accuracy whereas double provides 15

significant digits.

Numeric overflow

By applying arithmetic operator to value of a given data type, one could

obtain a result that falls outside of data type range values and hence cannot

be represents with same primitive data type. Such a situation is called

overflow.

Example:

byte a=125;

byte b=a+3; // numeric overflow

Data type range value of byte is -128 to 127, by adding 3 into byte data

type value i.e. 125, it is now 128, so it is overflow situation.


• Character Types

The type char is primitive data type that uses two bytes to store character.

Character constant varies between 0 to 255.

Each character is assigned a particular value according to ASCII (American

Standard Code for Information Interchange) codes.

Special Printing Characters

Character can be written by writing the character in single quotes. But some

characters are written in java program by using escape (\).

Escape character changes the meaning of character which follow its.

• String

String is a series of characters. These characters may be alphabets, digits,

blank spaces etc.

The string is enclosed within double quotes.

Example:

“My name is Pramod Rajput”, “Surat”, “Blue” etc.


• Boolean Data

The type boolean is used to test a particular condition during the execution

of the program. It works on true or false values. All comparison operators

return boolean values.

Note: for more details about data types open the following link

https://www.youtube.com/watch?v=-ABEZ1GTAOM&feature=youtu.be

➢ Identifiers

An identifier is a name given to a package, class, interface, method or

variable. An identifier is a sequence of one or more characters.

Naming rules for identifiers:

• Identifier may consist one or more than one letter, number and

underscore.

• The first character of the identifier must be a letter of the alphabet

(upper or lowercase) or an underscore ('_').

• Identifier names are case-sensitive.

• Try to use meaningful name.

• They must not be a keyword

• No blank spaces are allowed in an identifier name.

• Use of special character is not allowed.

• An Identifier can be any length.

➢ What is a Variable?

A variable is quantity which varies during execution of program. A variable is

the name of location where information is stored. Declaration of variable is

essential before using it in java program.

Syntax:

datatype variableName;

Example:

int value;

double salary;

int age;

https://www.youtube.com/watch?v=-ABEZ1GTAOM&feature=youtu.be


Assign value to a variable

The value to a variable can be assigned using = sign.

Syntax:

datatype variableName;

variableName = value;

Example:

int value; // two lines initialization

value=19;

datatype variableName=value;

Example:

double salary= 45000; //single line initialization

Default values are assigned to variables are as follows:

Initialize constant

A variable store a value that can change as a program executes, while a

constant store a value that cannot be changed.

Syntax:

final datatype variableName=value;

final int sales=17;


Declaring multiple variables

You can declare multiple variables in java.

Example:

int a, b, c;

Each variable is separated by comma.

Note: for more details about identifiers open the following link


➢ Java Reserved Words

Java reserve words are those words which cannot not be used as variable

name.

Figure:



➢ Punctuators

A punctuator is a token that has syntactic and semantic meaning to a

compiler but the exact meaning depending upon the context.

Punctuators also known as separators.

There are nine punctuators in java

Punctuators that terminates a statement in java is called statement

terminator. Semicolon (;) is a statement terminator in java.

Note: for more details about punctuators open the following link


➢ Data Type Conversions

When you assign a value of one data type to another, the two type might

not compatible to each other. If the data types are compatible, then java

will perform the conversions automatically known as Automatic type

conversions and if not then they need to be converted explicitly.

Widening or Automatic or Implicit Type Conversions

Implicit conversion take palace when two data types are automatically

converted.

Byte --> short --> int --> long --> float --> double

For example

int a=100;

long b=a; // implicit conversion

Narrowing or Explicit Type Conversions

If we want to assign a value of larger data type to a smaller data type we

perform explicit type conversion.

double --> float --> long --> int --> short --> byte

char and number are not compatible with each other.



double d= 100.24;

long a= (long) d; // explicit conversion

Note: for more details about data type conversions open the following link

https://www.youtube.com/watch?v=w2dKvQpm67E&feature=youtu.be

➢ ASCII Codes

There are 128 values in ASCII codes.

Note: for more details about ASCII code open the following link

https://www.youtube.com/watch?v=NEdrPb4D3Bg&feature=youtu.be

*********

➢ Java programs with Input method

1. Write a java program to calculate the area and circumference

of circle using input method Area= πr2 and Circumference= 2πr.

import java.io.*;

class pr1

{

public static void main(String args[]) throws IOException

{

InputStreamReader isr =new InputStreamReader(System.in);

BufferedReader br =new BufferedReader(isr);

System.out.println("Enter the radius of circle");

String s1= br.readLine();

double r= Double.parseDouble(s1);

double area, cf;

https://www.youtube.com/watch?v=w2dKvQpm67E&feature=youtu.be

https://www.youtube.com/watch?v=NEdrPb4D3Bg&feature=youtu.be


area=3.14*r*r;

cf=2*3.14*r;

System.out.println("The area of circle is="+area);

System.out.println("The circumference of circle is="+cf);

}

}

2. Write a java programs to find out area of triangle using input

method.

area of triangle=1/2*base*height

import java.io.*;

class pr2

{


{



System.out.println("Enter the base of triangle");


double b= Double.parseDouble(s1);

System.out.println("Enter the height of triangle");


double h= Double.parseDouble(s2);

double area;

area=1.0/2*b*h;

System.out.println("The area of triangle is="+area);

}

}


3. Write a java programs to find out volume of cuboid using input

method.

Volume of cuboid=l*b*h

import java.io.*;

class pr3

{


{



System.out.println("Enter the length of cuboid");


double l= Double.parseDouble(s1);

System.out.println("Enter the breadth of cuboid");



System.out.println("Enter the height of cuboid");


double h= Double.parseDouble(s3);

double volume;

volume=l*b*h;

System.out.println("The volume of cuboid is="+volume);

}

}


4. Write java program for swapping of two numbers using third

(temporary) variable with input method.

Note: if inputs are a=2 and b=5

Then output will be a=5 and b=2

Swapping means interchanging the values of variables

import java.io.*;

class pr4

{


{



System.out.println("Enter the first number");


int a= Integer.parseInt(s1);

System.out.println("Enter the second number");


int b= Integer.parseInt(s2);

int c;

c=a;

a=b;

b=c;

System.out.println("Number after swapping are");

System.out.println("a="+a);

System.out.println("b="+b);

}

}


5. Write java program for swapping of two numbers without

using third variable with input method.

import java.io.*;

class pr5

{


{



System.out.println("Enter the first number");


int a= Integer.parseInt(s1);

System.out.println("Enter the second number");


int b= Integer.parseInt(s2);

b=b-a;

a=a+b;

b=a-b;

System.out.println("Number after swapping are");

System.out.println("a="+a);

System.out.println("b="+b);

}

}

*********

Worksheet 1

1. What is token?

2. Give the examples of Hexadecimal constant?

3. How many bytes memory is occupied by int and long datatype?

4. How many bytes memory is occupied by double and char datatype?

5. What is the range of short datatype?

6. What is the range of int datatype?


7. What is numeric overflow?

8. What is the syntax for variable declaration?

9. What is the default value of char datatype?

10. What is full form of ASCII

Solution of worksheet 1

1. Tokens are the various java program elements which are identified by

the compiler.

2. 7FA, A4, 3F

3. int 4 bytes and long 8 bytes

4. double 8 bytes and char 2 bytes

5. -32768 to 32767

6. -231 to 231-1

7. By applying arithmetic operator to value of a given data type, one

could obtain a result that falls outside of data type range values and

hence cannot be represents with same primitive data type. Such a

situation is called overflow.

Example:

byte a=125;

byte b=a+3; // numeric overflow

8. datatype variableName;

Ex: int a;

9. \u0000

10. American Standard Code for Information Interchange.

*********

Worksheet 2

1. Write a java programs to find out cube of a number using input

method.

2. Write a java programs to find out area of rectangle using input

method.

area of rectangle=length*breadth

3. Write a java programs to find out volume of sphere using input

method.

Volume of sphere= 4/3*πr3


Solution of worksheet 2

1.

import java.io.*;

class pramodrajput

{


{



System.out.println("Enter the number");


int n= Integer.parseInt(s1);

int cube=n*n*n;

System.out.println("Cube of number is="+cube);

}

}

2.

import java.io.*;

class pramodrajput

{


{



System.out.println("Enter the breadth of rectangle");



System.out.println("Enter the length of rectangle");



double l= Double.parseDouble(s2);

double area;

area=l*b;

System.out.println("The area of rectangle is="+area);

}

}

3.

import java.io.*;

class pramodrajput

{


{



System.out.println("Enter the radius of sphere");


double r= Double.parseDouble(s1);

double volume;

volume=4.0/3*3.14*r*r*r;

System.out.println("The volume of sphere is="+volume);

}

}

**********

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