Arrays

Arrays

AU May-19, Marks 7

Arrays can be defined as a set of pair-index and the value. Two basic operations that can be performed on arrays are: Storing of data at desired location or index and retrieving data from desired location (index).

Advantages of Arrays

1. Elements can be retrieved or stored very efficiently in array with the help of index or memory location.

2. All the elements are stored at continuous memory locations. Hence searching of element from sequential organization is easy.

Disadvantages of Arrays

1. Insertion and deletion of elements becomes complicated due to sequential nature.

2. For storing the data large continuous free block of memory is required.

3. Memory fragmentation occurs if we remove the elements randomly.

Syntax

The syntax of declaring an array is

data_type name_of_array [size];

For example, int a [10]; double b[10] [10];

Here 'a' is the name of the array inside the square bracket size of the array is given. This array is of integer type i.e. all the elements are of integer type in array 'a'. Similarly arrays may be of user defined type, called as array of structure C supports both one dimensional and multidimensional arrays.

 

1. Initialization

• It is possible to initialize an array during declaration only. For example

int a[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

• The list of values, enclosed in braces {}, separated by commas, provides the initial values for successive elements of the array.

• If there are fewer initializers than elements in the array, the remaining elements are automatically initialized to 0. For example,

int a[10] = (0, 1, 2, 3, 4, 5, 6);

would initialize a[7], a[8], and a[9] to 0.

. When an array definition includes an initializer, the array dimension may be omitted, and the compiler will infer the dimension from the number of initializers. For example,

int b[ ] = {10, 11, 12, 13, 14};

would declare, define, and initialize an array b of 5 elements. Here only the dimension is omitted; the brackets [] remain to indicate that b is in fact an array.

 

2. Single Dimensional Arrays

Array can be one dimensional and two dimensional.

For example

You can visualize one dimensional array as :

Note that the elements in array are always stored in contiguous memory locations.

Now let us see how to handle this array. We will write a simple C program in which we are simply going to store the elements and then we will print those stored elements.

C Program

#include<stdio.h>

#include<conio.h>

main( )

{

int a[10],index;

clrscr( );

printf("\n Store The Elements In An Array a");

for(index=0;index < = 9;index++)

scanf("%d",&a[index]);

printf("\n You have stored these numbers in the array a");

for(index=0;index < =9;index++)

printf("\n %d", a[index]);

}

 

3. Two Dimensional Arrays

The two dimensional array is something which you can compare with the two storied building! Extra space which is arranged in rows and columns. Let us draw a figure which will represent the two dimensional array.

The syntax of two dimensional array is :

Data _ type Name_Of_array[row_size][column_size];

For example

int a[10][10];

By this allocation the memory block of 10 x 10 =100 is getting created. The nested for loops can be effectively used to access all the elements of an two dimensional array. We will take a sample example to explain this idea. bon atomolo orb

for(i=0;i<=2;i++)

{

for(j=0;j<=2;j++)

scanf("%d",&a[i][j]);

}

}

Execution of Nested for Loop

Initially the value of i=0 at that time

 j-0 it will store the element in a[0][0]

j-1 it will store the element in a[0][1]

j-2 it will store the element in a[0][2]

Next time i will be incremented by 1 and now i=1

Again

j=0 it will store the element in a[1][0]

j-1 it will store the element in a[1][1]

j-2 it will store the element in a[1][2]

Next time i will be incremented by 1 and now i=2

j=0 it will store the element in a[2][0]

j-1 it will store the element in a[2][1]

j-2 it will store the element in a[2][2]

Since now value of i and j has reached to 2 the scanning procedure will get terminated as condition is i<=2 and j<=2. Thus all the elements from a[0][0] to a[2][2] get scanned.

 

Ex. 1.10.1 How two dimensional arrays are created in C? Write a C program to generate a population survey having citizen's record stored as a collection of year-wise population.

Sol. : Two dimensional array - Refer section 1.10.3

#include <stdio.h>

int main( )

{

int arr[3][3],i,j;

for (i=0;i<3;i++)

{

printf("\nEnter the population for country#%d", (i+1));

for (j=0;j<3;j++)

{

printf("\n Enter the population for Year#%d", (j+1));

scanf("%d",&arr[i][j]);

}

}

printf("\n printing the population ....\n");

printf("\n\t country#1 country#2 country#3\n");

printf("\n-----------------------\n");

for(i=0;i<3;i++)

{

printf("Year#%d ", (i+1));

for (j=0;j<3;j++)

{

printf("\t%dL", arr[i][j]);

}

printf("\n");

}

return 0;

}