Page 141 - ComputerScience_Class_11

Array
Arrays can be defined as a collection of elements of the same data type stored under a single variable name. Each
element in the array is identified by its index (subscript) which helps to access or separate the values. When we declare
an array we create a structure that can store multiple values of the same type together.
The syntax to declare an array is as follows:

Primitive_Datatype variable_name[]= new Primitive_Datatype[size];
For example,

int ar[]= new int[10]; //it creates an integer array of 10 elements
Interface
An interface is an abstract class contains a combination of methods and variables. But the methods declared in an
interface have signatures only. By default, all methods in an interface are abstract and the variables are public, static
and final. For example,
interface fan
{
void show();
}
String
A string is a sequence of characters stored in a single variable. They are written within “ ” (double quotation marks).
Unlike C/C++, Java strings are not terminated with a null character. Syntax of declaring a string:
String <variable> = "sequence_of_characters";

6.4 ARITHMETIC EXPRESSION
The arithmetic expressions are the expressions that contain variables, constants and arithmetic operators. They are
used to perform mathematical calculations. For example,
int a = 5, b = 6;
double c;
c = (a+b)/2.0;

6.4.1 Types of Arithmetic Expressions
There are two types of arithmetic expressions.
• Pure arithmetic expression: When the variables and constants in an expression are of the same data type, then the
expression is known as a pure arithmetic expression. For example,

int a,b,c;
a = 100;
b = 200;
c = a+b;
In the above expression, all the variables are of integer type.
• Mixed arithmetic expression: When the variables and constants in an expression are of different data types, then
the expression is known as a mixed arithmetic expression. For example,
int a;
float b;
double c;
a = 100;
b = 200.20f;
c = a + b;
In the above expression, the variables are of different data types.

Primitive Values, Wrapper Classes, Types and Casting 139