### Tutorial Playlist

Arrays in data structures help solve some high-level problems like the "longest consecutive subsequence" program or some easy tasks like arranging the same things in ascending order. The concept is to collect many objects of the same kind.

## What Are Arrays in Data Structures?

An array is a linear data structure that collects elements of the same data type and stores them in contiguous and adjacent memory locations. Arrays work on an index system starting from 0 to (n-1), where n is the size of the array.

It is an array, but there is a reason that arrays came into the picture.

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## Why Do You Need an Array in Data Structures?

Let's suppose a class consists of ten students, and the class has to publish their results. If you had declared all ten variables individually, it would be challenging to manipulate and maintain the data.

If more students were to join, it would become more difficult to declare all the variables and keep track of it. To overcome this problem, arrays came into the picture.

## What Are the Types of Arrays?

There are majorly two types of arrays, they are:

### One-Dimensional Arrays:

You can imagine a 1d array as a row, where elements are stored one after another.

### Multi-Dimensional Arrays:

These multi-dimensional arrays are again of two types. They are:

#### Two-Dimensional Arrays:

You can imagine it like a table where each cell contains elements.

#### Three-Dimensional Arrays:

You can imagine it like a cuboid made up of smaller cuboids where each cuboid can contain an element.

In this "arrays in data structures" tutorial, you will work around one-dimensional arrays.

## How Do You Declare an Array?

Arrays are typically defined with square brackets with the size of the arrays as its argument.

Here is the syntax for arrays:

1D Arrays: int arr[n];

2D Arrays: int arr[m][n];

3D Arrays: int arr[m][n][o];

## How Do You Initialize an Array?

You can initialize an array in four different ways:

• ### Method 1:

int a[6] = {2, 3, 5, 7, 11, 13};

• ### Method 2:

int arr[]= {2, 3, 5, 7, 11};

• ### Method 3:

int n;

scanf(“%d”,&n);

int arr[n];

for(int i=0;i<5;i++)

{

scanf(“%d”,&arr[i]);

}

int arr[5];

arr[0]=1;

arr[1]=2;

arr[2]=3;

arr[3]=4;

arr[4]=5;

## How Can You Access Elements of Arrays in Data Structures?

You can access elements with the help of the index at which you stored them. Let's discuss it with a code:

#include<stdio.h>

int main()

{

int a[5] = {2, 3, 5, 7, 11};

printf(“%d\n”,a[0]); // we are accessing

printf(“%d\n”,a[1]);

printf(“%d\n”,a[2]);

printf(“%d\n”,a[3]);

printf(“%d”,a[4]);

return 0;

}

In this “Arrays in Data structures” tutorial, you have seen the basics of array implementation, now you will perform operations on arrays.

## What Operations Can You Perform on an Array?

• Traversal
• Insertion
• Deletion
• Searching
• Sorting

### Traversing the Array:

Traversal in an array is a process of visiting each element once.

Code:

#include<stdio.h>

int main()

{

int a[5] = {2, 3, 5, 7, 11};

for(int i=0;i<5;i++)

{

//traversing ith element in the array

printf(“%d\n”,a[i]);

}

return 0;

}

### Insertion:

Insertion in an array is the process of including one or more elements in an array.

Insertion of an element can be done:

• At the beginning
• At the end and
• At any given index of an array.

#### At the Beginning:

Code:

#include<stdio.h>

int main()

{

int array[10], n,i, item;

printf("Enter the size of array: ");

scanf("%d", &n);

printf("\nEnter Elements in array: ");

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

{

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

}

printf("\n enter the element at the beginning");

scanf("%d", &item);

n++;

for(i=n; i>1; i--)

{

array[i-1]=array[i-2];

}

array[0]=item;

printf("resultant array element");

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

{

printf("\n%d", array[i]);

}

getch();

return 0;

}

#### At the End:

Code:

#include<stdio.h>

#include<conio.h>

int main()

{

int array[10], i, values;

printf("Enter 5 Array Elements: ");

for(i=0; i<5; i++)

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

printf("\nEnter Element to Insert: ");

scanf("%d", &values);

array[i] = values;

printf("\nThe New Array is:\n");

for(i=0; i<6; i++)

printf("%d ", array[i]);

getch();

return 0;

}

#### At a Specific Position:

Code:

#include <stdio.h>

int main()

{

int array[100], pos, size, val;

printf("Enter size of the array:");

scanf("%d", &size);

printf("\nEnter %d elements\n", size);

for (int i = 0; i < size; i++)

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

printf("Enter the insertion location\n");

scanf("%d", &pos);

printf("Enter the value to insert\n");

scanf("%d", &val);

for (int i = size - 1; i >= pos - 1; i--)

array[i+1] = array[i];

array[pos-1] = val;

printf("Resultant array is\n");

for (int i = 0; i <= size; i++)

printf("%d\n", array[i]);

return 0;

}

### Deletion:

Deletion of an element is the process of removing the desired element and re-organizing it.

You can also do deletion in different ways:

• At the beginning
• At the end

#### At the Beginning:

#include<stdio.h>

int main()

{

int n,array[10];

printf("enter the size of an array");

scanf("%d" ,&n);

printf("enter elements in an array");

for(int i=0;i<n;i++)

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

n--;

for(int i=0;i<n;i++)

array[i]=array[i+1];

printf("\nafter deletion ");

for(int i=0;i<n;i++)

printf("\n%d" , array[i]);

}

#### At the End:

#include<stdio.h>

int main()

{

int n,array[10];

printf("enter the size of an array");

scanf("%d" ,&n);

printf("enter elements in an array");

for(int i=0;i<n;i++)

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

printf("\nafter deletion array elements are");

for(int i=0;i<n-1;i++)

printf("\n%d" , array[i]);

}

### Searching for an Element

The method of searching for a specific value in an array is known as searching.

There are two ways we can search in an array, they are:

• Linear search
• Binary search

#### Linear Search:

Code:

#include <stdio.h>

int linear(int a[], int n, int x)

{

for (int i = 0; i < n; i++)

if (a[i] == x)

return i;

return -1;

}

int main(void)

{

int a[] = { 2, 3, 4, 10, 40 };

int x = 10;

int n = sizeof(a) / sizeof(a[0]);

// Function call

int result = linear(a, n, x);

if(result == -1)

{

printf("Element is not present in array");

}

else

{

printf("Element found at index: %d", result);

}

return 0;

}

#### Binary Search:

#include <stdio.h>

int binary(int a[], int lt, int rt, int k)

{

if (rt >= lt) {

int mid = lt + (rt - l) / 2;

// check If element is at the middle

if (a[mid] == k)

return mid;

//check if element is at the left side of mid

if (a[mid] > x)

return binary(a, lt, mid - 1, k);

// Else element is at the right side of mid

return binary(a, mid + 1, rt, k);

}

// if element not found

return -1;

}

int main(void)

{

int a[] = { 2, 3, 5, 7, 11 };

int n = sizeof(a) / sizeof(a[0]);

int k = 11;

int res = binary(arr, 0, n - 1, k);

if(res == -1)

{

printf("Element is not found")

}

else

{

printf("Element found at index %d",res);

}

return 0;

}

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### Sorting:

Sorting in an array is the process in which it sorts elements in a user-defined order.

Code:

#include <stdio.h>

void main()

{

int temp, size, array[100];

printf("Enter the size \n");

scanf("%d", &size);

printf("Enter the numbers \n");

for (int i = 0; i < size; ++i)

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

for (int i = 0; i < size; ++i)

{

for (int j = i + 1; j < size; ++j)

{

if (array[i] > array[j])

{

temp = array[i];

array[i] = array[j];

array[j] = temp;

}

}

}

printf("sorted array:\n");

for (int i = 0; i < size; ++i)

printf("%d\n", array[i]);

}

## What Are the Advantages of Arrays in Data Structures?

• Arrays store multiple elements of the same type with the same name.
• You can randomly access elements in the array using an index number.
• Array memory is predefined, so there is no extra memory loss.
• Arrays avoid memory overflow.
• 2D arrays can efficiently represent the tabular data.

## What Are the Disadvantages of Arrays in Data Structures?

• The number of elements in an array should be predefined
• An array is static. It cannot alter its size after declaration.
• Insertion and deletion operation in an array is quite tricky as the array stores elements in continuous form.
• Allocating excess memory than required may lead to memory wastage.
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### Next Steps

"Linked list Data structures" can be your next stop. Linked lists are made up of nodes that point to the next node. Linked lists are dynamic and have faster insertion/deletion time complexities.

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