C program to Insert an element in an Array

Given an array arr of size n, this article tells how to insert an element x in this array arr at a specific position pos.

An array is a collection of items stored at contiguous memory locations. In this article, we will see how to insert an element in an array in C.

Follow the below steps to solve the problem:

• 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(towards right), 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.

Below is the implementation of the above approach:

C

// C Program to Insert an element
// at a specific position in an Array

#include <stdio.h>

int main()
{
    int arr[100] = { 0 };
    int i, x, pos, n = 10;

    // initial array of size 10
    for (i = 0; i < 10; i++)
        arr[i] = i + 1;

    // print the original array
    for (i = 0; i < n; i++)
        printf("%d ", arr[i]);
    printf("\n");

    // element to be inserted
    x = 50;

    // position at which element
    // is to be inserted
    pos = 5;

    // increase the size by 1
    n++;

    // shift elements forward
    for (i = n - 1; 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");

    return 0;
}

Output

1 2 3 4 5 6 7 8 9 10 
1 2 3 4 50 5 6 7 8 9 10 

Time Complexity: O(N), Where N is the number of elements in the array
Auxiliary Space: O(1)