Learn-c-by-examples-linked-list-update-program-in-c

リンクリストのアイテムを更新するプログラム

実装

このアルゴリズムの実装は以下のとおりです-

#include <stdio.h>
#include <stdlib.h>

struct node {
   int data;
   struct node *next;
};

struct node *head = NULL;
struct node *current = NULL;

//Create Linked List
void insert(int data) {
  //Allocate memory for new node;
   struct node *link = (struct node*) malloc(sizeof(struct node));

   link->data = data;
   link->next = NULL;

  //If head is empty, create new list
   if(head==NULL) {
      head = link;
      return;
   }

   current = head;

  //move to the end of the list
   while(current->next!=NULL)
      current = current->next;

  //Insert link at the end of the list
   current->next = link;
}

void display() {
   struct node *ptr = head;

   printf("\n[head] =>");
  //start from the beginning
   while(ptr != NULL) {
      printf(" %d =>",ptr->data);
      ptr = ptr->next;
   }

   printf(" [null]\n");
}

void update_data(int old, int new) {
   int pos = 0;

   if(head==NULL) {
      printf("Linked List not initialized");
      return;
   }

   current = head;
   while(current->next!=NULL) {
      if(current->data == old) {
         current->data = new;
         printf("\n%d found at position %d, replaced with %d\n", old, pos, new);
         return;
      }

      current = current->next;
      pos++;
   }

   printf("%d does not exist in the list\n", old);
}

int main() {
   insert(10);
   insert(20);
   insert(30);
   insert(1);
   insert(40);
   insert(56);

   display();
   update_data(40, 44);
   display();

   return 0;
}

出力

プログラムの出力は次のようになります-

[head] => 10 => 20 => 30 => 1 => 40 => 56 => [null]

40 found at position 4, replaced with 44

[head] => 10 => 20 => 30 => 1 => 44 => 56 => [null]