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

In C++, an array is a data structure that is used to store multiple values of similar data types in a contiguous memory location. In this article, we are going to discuss how to remove a value from an array in C++.

Example:

Input:  arr[] = {3, 1, 2, 5, 90}, x = 2
Output: arr[] = {3, 1, 5, 90}

Remove an Element from an Array in C++

To remove a value from an array in C++, we first search ‘x’ in the array, then move elements that are on the right side of x to one position towards the front (i.e. towards the left).

Approach

• Search for the element in the array by iterating over the array using a for loop.
• Check if the element is found in the array.
• If the element is found, reduce the size of the array and move all elements one space ahead.
• Return the new size of the array.

C++ Program to Remove an Element from Array

C++

// C++ program to illustrate how to remove a given element
// from an array
#include <array>
#include <iostream>
using namespace std;

// This function removes an element x from arr[] and
// returns new size after removal (size is reduced only
// when x is present in arr[]
int deleteElement(int arr[], int n, int x)
{
    // Search x in array
    int i;
    for (i = 0; i < n; i++)
        if (arr[i] == x)
            break;

    // If x found in array
    if (i < n) {
        // reduce size of array and move all
        // elements on space ahead
        n = n - 1;
        for (int j = i; j < n; j++)
            arr[j] = arr[j + 1];
    }

    return n;
}

// Driver code
int main()
{
    int arr[] = { 11, 15, 6, 8, 9, 10 };
    int n = sizeof(arr) / sizeof(arr[0]);
    int x = 6;

    cout << "Before Modification array is \n";
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";

    // Delete x from arr[]
    n = deleteElement(arr, n, x);

    cout << "\n After Removal of " << x << " from array\n";
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";

    return 0;
}

Output

Before Modification array is 
11 15 6 8 9 10 
 After Removal of 6 from array
11 15 8 9 10 

Time Complexity: O(N)
Auxiliary Space: O(1)