Arrays

• An array is a collection of similar data elements.
• These data elements have the same data type.
• Element − Each item stored in an array is called an element.
• Index − Each location of an element in an array has a
numerical index, which is used to identify the element.
• The elements of the array are stored in consecutive
memory locations and are referenced by an index
(subscript).
2
DEFINITION

ARRAY REPRESENTATION
Array Name Elements
int marks[10] = { 56, 59, 69, 78, 96, 43, 90, 88, 94, 70}
Data type Array Size
Index starts with 0
Mark1 mark2 mark3 mark4 mark5 mark6 mark7 mark8 mark9 mark10
index [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]
3
56 59 69 78 96 43 90 88 94 70Elements
Element name

LIMITATIONS OF ARRAY
• Arrays are generally used when we want to store large
amount of similar type of data.
• But they have the following limitations:
• Arrays are of fixed size.
• Data elements are stored in contiguous memory
locations which may not be always available.
• Insertion and deletion of elements can be problematic
because of shifting of elements from their positions.
4

EXAMPLE CODE 5
With Array
#include <stdio.h>
void main ()
{
int marks[6] = {56,78,88,76,56,89);
int i,tot=0;
float avg;
for (i=0; i<6; i++ )
{
tot=tot+ marks[i];
}
avg=tot/6;
printf(avg);
}
Without Array
#include <stdio.h>
void main ()
{
int marks_1 = 56, marks_2 = 78, marks_3 = 88,
marks_4 = 76, marks_5 = 56, marks_6 = 89;
float avg = (marks_1 + marks_2 + marks_3 +
marks_4 + marks_5 +marks_6) / 6 ;
printf(avg);
}

TYPES OF ARRAYS
• One Dimensional Arrays - Linear List
• Two Dimensional Arrays – Table, Matrix
• Three Dimensional Arrays – Multi Dimensional
6

TWO DIMENSIONAL ARRAYS
7
// Different ways to initialize two-
dimensional array
int c[2][3] = {{1, 3, 0}, {-1, 5, 9}};
int c[][3] = {{1, 3, 0}, {-1, 5, 9}};
int c[2][3] = {1, 3, 0, -1, 5, 9};
//Declaration of 2D Array
float x[3][4];
C1 C2 C3 C4
R1 X[0][0] X[0][1] X[0][2] X[0][3]
R2 X[1][0] X[1][1] X[1][2] X[1][3]
R3 X[2][0] X[2][1] X[2][2] X[2][3]

THREE DIMENSIONAL ARRAY 8
// Initialization of 3D Array with Input Values
int test[2][3][4] = { {{3, 4, 2, 3}, {0, -3, 9, 11},
{23, 12, 23, 2}}, {{13, 4, 56, 3}, {5, 9, 3, 5}, {3,
1, 4, 9}}};
// Declaration
float y[2][4][3];

OPERATIONS
• Traversing: It prints all the array elements one after another.
• Inserting: It adds an element at given index.
• Deleting: It is used to delete an element at given index.
• Searching: It searches for an element(s) using given index or by value.
• Updating: It is used to update an element at given index.
9

TRAVERSAL 10
// Access the first element of the
array
printf("%d", mark[0]);
// Access the third element of the
array printf("%d", mark[2]);
// Access ith element of the array
printf("%d", mark[i-1]);
#include <stdio.h>
void main()
{
int array[10];
int i;
printf("enter the elements n");
for (i = 0; i < 10; i++)
scanf("%d", &array[i]);
printf(“Elements of the array n");
for (i = 0; i < 10; i =i++)
printf( "%dn", array[i]) ;
}

INSERTION
• First get the element to be inserted, say x
• Then get the position at which this element is to be inserted, say pos
• Then shift the array elements from this position to one position
forward, and do this for all the other elements next to pos.
• Insert the element x now at the position pos, as this is now empty.
11
12 87 14 68 73 90 12 3
12 87 14 68 73 50 90 12 3
X= 50
Pos = 5

12CODE
// element to be inserted
x = 50;
// position at which elements
to be inserted
pos = 5;
// increase the size by 1
n++;
// shift elements forward
for (i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// insert x at pos
arr[pos - 1] = x;
// print the updated array
for (i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("n");

DELETION 13
Step by step descriptive logic to remove element from array.
• Move to the specified location which you want to remove in given
array.
• Copy the next element to the current element of array. Which is you
need to perform array[i] = array[i + 1].
• Repeat above steps till last element of array.
• Finally decrement the size of array by one.

14
12 87 14 68 73 50 90
12 14 68 73 50 90 90
Element to be deleted
12 14 68 73 50 90 90

15
printf("Enter the element position to delete :
");
scanf("%d", &pos);
/* Invalid delete position */
if(pos < 0 || pos > size)
{
printf("Invalid position! Please enter position
between 1 to %d", size);
}
else
{
/* Copy next element value to current
element */
for(i=pos-1; i<size-1; i++)
{
arr[i] = arr[i + 1];
}
/* Decrement array size by 1 */
size--;
}
/* Print array after deletion */
printf("nElements of array after delete are :
");
for(i=0; i<size; i++)
{
printf("%dt", arr[i]);
}

SEARCHING
• Input size and elements in array from user.
• Store it in some variable say size and arr.
• Input number to search from user in some variable say toSearch.
• Define a flag variable as found = 0.
• Run loop from 0 to size.
• Inside loop check if current array element is equal to searched
number or not.
• Which is if(arr[i] == toSearch) then set found = 1 flag and
terminate from loop.
• Since element is found no need to continue further.
• Outside loop if(found == 1) then element is found otherwise not.
16

UPDATION
• Consider A is a linear array with N elements
• K is a positive integer such that K<=N.
• Following is the algorithm to update an element available at the
Kth position of A.
17
printf("The original array elements are :n");
for(i = 0; i<n; i++)
{
printf("A[%d] = %d n", i, LA[i]);
}
A[k-1] = item;
printf("The array elements after updation :n");
for(i = 0; i<n; i++)
{
printf("A[%d] = %d n", i, LA[i]);
} }

Arrays

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