C Program For Deleting A Node In A Linked List - GeeksforGeeks

26 Dec, 2021
We have discussed Linked List Introduction and Linked List Insertion in previous posts on a singly linked list.Let us formulate the problem statement to understand the deletion process. Given a ‘key’, delete the first occurrence of this key in the linked list. 
Iterative Method:To delete a node from the linked list, we need to do the following steps. 1) Find the previous node of the node to be deleted. 2) Change the next of the previous node. 3) Free memory for the node to be deleted. 
Since every node of the linked list is dynamically allocated using malloc() in C, we need to call free() for freeing memory allocated for the node to be deleted.
C
// A complete working C program// to demonstrate deletion in// singly linked list#include <stdio.h>#include <stdlib.h>  // A linked list nodestruct Node {    int data;    struct Node* next;};  /* Given a reference (pointer to pointer) to the head of a   list and an int, inserts a new node on the front of the   list. */void push(struct Node** head_ref, int new_data){    struct Node* new_node        = (struct Node*)malloc(sizeof(struct Node));    new_node->data = new_data;    new_node->next = (*head_ref);    (*head_ref) = new_node;}  /* Given a reference (pointer to pointer) to the head of a   list and a key, deletes the first occurrence of key in   linked list */void deleteNode(struct Node** head_ref, int key){    // Store head node    struct Node *temp = *head_ref, *prev;      // If head node itself holds the key to be deleted    if (temp != NULL && temp->data == key) {        *head_ref = temp->next; // Changed head        free(temp); // free old head        return;    }      // Search for the key to be deleted, keep track of the    // previous node as we need to change 'prev->next'    while (temp != NULL && temp->data != key) {        prev = temp;        temp = temp->next;    }      // If key was not present in linked list    if (temp == NULL)        return;      // Unlink the node from linked list    prev->next = temp->next;      free(temp); // Free memory}  // This function prints contents of linked list starting// from the given nodevoid printList(struct Node* node){    while (node != NULL) {        printf(" %d ", node->data);        node = node->next;    }}  // Driver codeint main(){    /* Start with the empty list */    struct Node* head = NULL;      push(&head, 7);    push(&head, 1);    push(&head, 3);    push(&head, 2);      puts("Created Linked List: ");    printList(head);    deleteNode(&head, 1);    puts("Linked List after Deletion of 1: ");    printList(head);    return 0;}
Created Linked List: 
 2  3  1  7 
Linked List after Deletion of 1: 
 2  3  7
Please refer complete article on Linked List | Set 3 (Deleting a node) for more details!
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