How to Delete an Element from an Array in C++?

In C++, arrays are data structures that allow users to store data of the same type in contiguous memory locations. In this article, we will learn how to delete an element from an array in C++.

Example:

Input:
myarr = {20, 5, 1, 10, 15};
Target: 1
Output:
Array after deletion: 20 5 10 15

Remove an Element from an Array in C++

In C++, arrays are static, which means we cannot change their size once declared. Therefore, technically, we cannot delete an element from an array. However, we can mimic this behavior to delete element from the array in C++ using the below approach:

Approach

• Find the index of the element you want to delete from the array.
• Shift all the elements after that index to the left.
• Update the size of the array after deletion if you are keeping it.

C++ Program to Delete an Element from an Array

The following program illustrates how to delete an element from an array in C++.

C++

// C++ Program to illustrate how to delete an element from
// an array
#include <algorithm>
#include <iostream>
using namespace std;

// Function to delete an element from an array
void deleteElement(int arr[], int& size, int element)
{
    int indexToDelete = -1;

    // Find the index of the element to delete
    int* ptr = find(arr, arr + size, element);
    indexToDelete = ptr - arr;
    // Print error if the element to delete was not found in
    // the array
    if (indexToDelete > size - 1) {
        cout << "Element not found in the array." << endl;
        return;
    }

    // Shift elements to the left starting from the index to
    // be deleted
    for (int i = indexToDelete; i < size - 1; ++i) {
        arr[i] = arr[i + 1];
    }

    // Update the size of the array
    --size;
}

// driver code
int main()
{
    // Initialize an array
    int arr[] = { 20, 5, 1, 10, 15 };

    // Find the size of the array
    int size = sizeof(arr) / sizeof(arr[0]);

    // Print the array before deletion
    cout << "Array before deletion:";
    for (int i = 0; i < size; ++i) {
        cout << arr[i] << " ";
    }
    cout << endl;

    // Declare the element you want to delete from the array
    int target = 1;

    // Call the deleteElement function to delete the element
    deleteElement(arr, size, target);

    // Print the updated array after deletion
    cout << "Array after deletion:";
    for (int i = 0; i < size; ++i) {
        cout << arr[i] << " ";
    }

    return 0;
}

Output

Array before deletion:20 5 1 10 15 
Array after deletion:20 5 10 15 

Time Complexity: O(N), where N is the size of the array.
Auxiliary Space: O(1)