C Program to Insert an element in array

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.
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.

For example we have to insert 100 at 3rd position.

Algorithm

Here’s how to do it.
 

1. First get the element to be inserted, say x
2. Then get the position at which this element is to be inserted, say pos
3. Then shift the array elements from this position to one position forward, and do this for all the other elements next to pos.
4. Insert the element x now at the position pos, as this is now empty.

Below is the implementation of the above approach:

// 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

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