Question

You are given four files: linked-list.h linked-list. c find-ї ast-node.c , and a , , Makefile . The program is missing a definition to the following function, that you need to implement: struct node *find_last (struct node *list, int n); where node is defined as: struct node ( int value; char marker; //used to differentiate nodes struct node *next; The list parameter points to a linked list. The function must return a pointer to the LAST node that contains n ; it must return NULL if n doesn't appear in the list. Given the main function provided, here is how your program should behave Enter number you want to search for:5 Node found: value 5 and markera Remember that the add_to_list function that is taken from the book adds nodes to the beginning of the linked list. Running valgrind on your program will show that the current program has memory leaks. Fix the program such that it has no memory leaks

****find_last_node.c

#include <stdio.h>
#include "linked_list.h"

int main(){
  
   struct node *linked_list = NULL;

   linked_list = add_to_list(linked_list, 5, 'a');
   linked_list = add_to_list(linked_list, 10, 'b');
   linked_list = add_to_list(linked_list, 4, 'c');
   linked_list = add_to_list(linked_list, 10, 'd');
   linked_list = add_to_list(linked_list, 5, 'e');
   linked_list = add_to_list(linked_list, 7, 'f');
   linked_list = add_to_list(linked_list, 5, 'g');
   linked_list = add_to_list(linked_list, 3, 'h');

   int search_number;
   printf("Enter number you want to search for:");
   scanf("%d", &search_number);

   struct node *last_node = find_last(linked_list, search_number);
   if (last_node != NULL)
   {
       printf("Node found: value = %d and marker = %c\n", last_node->value, last_node->marker);
   }else{
       printf("Number not found!\n");
   }
  
   //running your program using valgrind will show you memory leaks. You need to make sure
//you free any allocated memory before you exit the program

****linked_list.c

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

struct node *add_to_list(struct node *list, int n, char marker){
   struct node *new_node;
   new_node = malloc(sizeof(struct node));

   if(new_node == NULL){
       printf("Error: malloc failed in add_to_list\n");
       exit(EXIT_FAILURE);
   }

   new_node->value = n;
   new_node->marker = marker;
   new_node->next = list;

   return new_node;
}

****linked_list.h

#ifndef __LINKED_LIST__
#define __LINKED_LIST__

struct node{
int value;
char marker;
struct node *next;
};

struct node *add_to_list(struct node *list, int n, char marker);
struct node *find_last(struct node *list, int n);
#endif

Answer 1

(Note: I added code to linked_list.c.The add to list function adds element at head.So I wrote find_last function which parses the linked list till the last element and returns last occurrence of value n. If there is no n value in linked list returns NULL.

In find_last_node.c add linked_list.c in header section. I added it so please copy my whole code and run it it will execute perfectly.

If you need any changes please comment I will modify the code.

If the program works fine Please up vote. Thank you.

linked_list.h:

#ifndef __LINKED_LIST__
#define __LINKED_LIST__

struct node{
int value;
char marker;
struct node *next;
};

struct node *add_to_list(struct node *list, int n, char marker);
struct node *find_last(struct node *list, int n);
#endif

linked_list.c:

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

struct node *add_to_list(struct node *list, int n, char marker){
   struct node *new_node;
   new_node = malloc(sizeof(struct node));

   if(new_node == NULL){
       printf("Error: malloc failed in add_to_list\n");
       //exit(EXIT_FAILURE);
   }
   new_node->value = n;
   new_node->marker = marker;
   new_node->next = list;
   return new_node;
}
struct node *find_last(struct node *list, int n){
   struct node *new_node;  
   while (list != NULL)
{
      if(list->value==n)
      {
      new_node = list;//new_node stores the last occurence of n value.
      }
     list = list->next;
}
   return new_node;
}

find_last_node.c:

#include<stdio.h>
#include<stdlib.h>
#include"linked_list.h"
#include"linked_list.c"

int main(){

   struct node *linked_list = NULL;

   linked_list = add_to_list(linked_list, 5, 'a');
   linked_list = add_to_list(linked_list, 10, 'b');
   linked_list = add_to_list(linked_list, 4, 'c');
   linked_list = add_to_list(linked_list, 10, 'd');
   linked_list = add_to_list(linked_list, 5, 'e');
   linked_list = add_to_list(linked_list, 7, 'f');
   linked_list = add_to_list(linked_list, 5, 'g');
   linked_list = add_to_list(linked_list, 3, 'h');
   int search_number;
   printf("Enter number you want to search for:");
   scanf("%d", &search_number);

   struct node *last_node = find_last(linked_list, search_number);
   if (last_node != NULL)
   {
       printf("Node found: value = %d and marker = %c\n", last_node->value, last_node->marker);
   }else{
       printf("Number not found!\n");
   }
}

Output:

File Edit View Search Termina Help shyam@shyam:~/Docunentss gcc find_last_node.c shyan@shyam: /Documents ./a.out Enter number you want to search for:5 Node found: value 5 and marker - a shyan@shyam~/Docunents$ -/a.out Enter number you want to search for:10 Node found: value 10 and markerb shyan@shyam: /Documents$ ./a.out Enter number you want to search for:12 Number not found! shyam@shyam:~/Documents$ |