Write a function to delete a Linked List

• Difficulty Level : Basic
• Last Updated : 18 May, 2021

Algorithm For C/C++: Iterate through the linked list and delete all the nodes one by one. The main point here is not to access the next of the current pointer if the current pointer is deleted.
In Java and Python, automatic garbage collection happens, so deleting a linked list is easy. Just need to change head to null.

Implementation: 

• C++
• C
• Java
• Python3
• C#
• Javascript

// C++ program to delete a linked list

#include <bits/stdc++.h>

using namespace std;

/* Link list node */

class Node {

public:

    int data;

    Node* next;

};

/* Function to delete the entire linked list */

void deleteList(Node** head_ref)

{

    /* deref head_ref to get the real head */

    Node* current = *head_ref;

    Node* next = NULL;

    while (current != NULL)

    {

        next = current->next;

        free(current);

        current = next;

    }

    /* deref head_ref to affect the real head back

        in the caller. */

    *head_ref = NULL;

}

/* Given a reference (pointer to pointer) to the head

of a list and an int, push a new node on the front

of the list. */

void push(Node** head_ref, int new_data)

{

    /* allocate node */

    Node* new_node = new Node();

    /* put in the data */

    new_node->data = new_data;

    /* link the old list off the new node */

    new_node->next = (*head_ref);

    /* move the head to point to the new node */

    (*head_ref) = new_node;

}

/* Driver code*/

int main()

{

    /* Start with the empty list */

    Node* head = NULL;

    /* Use push() to construct below list

    1->12->1->4->1 */

    push(&head, 1);

    push(&head, 4);

    push(&head, 1);

    push(&head, 12);

    push(&head, 1);

    cout << "Deleting linked list";

    deleteList(&head);

    cout << "\nLinked list deleted";

}

// This is code is contributed by rathbhupendra

Output

Deleting linked listLinked list deleted

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