Array

 Array:

            In many applications, we need to handle a large volume of data in terms of reading, processing and printing. To process such large amount of data, we need a powerful data type that facilitate efficient sorting, accessing and manipulation of data items. C++ supports a derived data type known as array that can be used for such applications.

            Array is an important part of almost all programming language. It provides an powerful feature and can be used to form complex data structures like stack and queue.

Definition:

An array can be defined as a collection of homogeneous (similar type) elements.

An array is a fixed size sequenced collection of elements of the same data type.

            This means that an array can store all integers, all floats, all characters or any other data type, but all of same type. Arrays are always stored at consecutive memory locations. Array can stores multiple values which can be referenced by a single name followed by an index or subscript, specified inside the square brackets i.e. [1].

Declaration of Array:

Syntax:

Data_type array_name [size];

Data_type is type of elements to be stored in the array, size specifies the number of elements to be stored in the array. Size is also known as subscript and it must be an integer value. The subscripts of an array starts from 0 onwards.

For Example:

int num[10];

            The array will store ten integer values, its name is num. The first element of an array have the subscript 0. To access particular element in array we give subscript value like,

            array_name[subscript];         

For Example:

num[5];

            The first element in every array is the 0^th element. Thus, the first element of array num is referred to as num[ 0 ], the second element of array num is referred to as num[ 1 ], the fifth element of array  num is referred to as num[ 4 ], and, in general, the n^th element of array num is referred to as    num[ n - 1 ] i.e. num[9].

The size of an array can be determined as follows:

            size=(upperbound – lowerbound) +1

For Example:

            size of array num=( 9 – 0 ) + 1 = 10

Initializing Array:

            ANSI C allows automatic array variable to be initialized in declarations by constants. These initializing expression must be constant values. The constants are specified within braces and separated by commas.

For Example:

            int num[10]={12, 23, 25, 27, 30, 32, 89, 40};

            char name[10]={‘P’, ’A’, ’T’, ’I’, ’L’};

            Each constant in the brace is assigned, in sequence, to an element of the array starting with index 0. If there is not enough constants for whole array, the remaining elements of array are initialized to 0. 

Accessing Array Elements:

Individual elements of an array can be accessed using following syntax:

Syntax:

            array_name[index/subscript];

For Example:

            num[3] = 5;                              //To assign value to array

cin>>num[3];                           // To read a particular value

cou<<num[3];                          // To write a particular value

Program:

#include<iostream.h>

int main()

{

            int a[4];

            int i;

            for ( i = 0; i < 4; i++ )

            {

                        a[i] = 0;

}

            for ( i = 0; i < 4; i++ )

            {

                        cout<<"a = "<<a[i];

}

            return 0;

}