Implementing circular linked list but while loop is running ininitely

Question

1.00/5 (1 vote)

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#include <stdio.h> 
#include <stdlib.h> 
struct Node 
{ 
int data; 
struct Node *ptr; 
}; 
 
void display_linkedList(struct Node *head) 
{ 
 
struct Node *temp = head; 
 
while ((temp->ptr) != head) 
{ 
printf("ELEMENT IS %d \n", temp->data); 
temp = temp->ptr; 
} 
 
printf("ELEMENT IS %d \n", temp->data); 
free(temp); 
} 
struct Node *insertion_At_the_start(struct Node *head, int value) 
{ 
struct Node *n; 
n = (struct Node *)malloc(sizeof(struct Node *)); //creation of new node 
n->data = value; 
 
 
struct Node *temp = head; 
 
while (temp->ptr != head) 
{ 
 
temp = temp->ptr; 
} 
 
 
 
temp->ptr = n; 
n->ptr = head; 
 
return n; 
} 
struct Node *insertion_At_the_end(struct Node *head, int value) 
{ 
struct Node *n; 
n = (struct Node *)malloc(sizeof(struct Node *)); //creation of new node 
n->data = value; 
n->ptr = head; 
 
 
struct Node *temp = head; 
 
while ((temp->ptr) != head) 
{ 
printf("!"); 
temp = temp->ptr; 
} 
 
n->ptr = temp->ptr; 
 
 
return head; 
} 
int main(int argc, char const *argv[]) 
{ 
struct Node *head; 
struct Node *second; 
struct Node *third, *fourth; 
 
head = (struct Node *)malloc(sizeof(struct Node)); 
second = (struct Node *)malloc(sizeof(struct Node)); 
 
third = (struct Node *)malloc(sizeof(struct Node)); 
 
fourth = (struct Node *)malloc(sizeof(struct Node)); 
 
head->data = 1; 
head->ptr = second; 
 
second->data = 2; 
second->ptr = third; 
 
third->data = 3; 
third->ptr = fourth; 
 
fourth->data = 4; 
fourth->ptr = head; 
 
printf("\nORIGINAL CIRCULAR LINKED LIST IS ----------------------------------\n"); 
display_linkedList(head); 
 
printf("\nCIRCULAR LINKED LIST AFTER INSERTION AT START IS ----------------------------------\n"); 
 
display_linkedList(insertion_At_the_start(head, 111111)); 
 
display_linkedList(insertion_At_the_end(head, 5555)); 
return 0; 
}

What I have tried:

i have tired all sorts of things but this issue is not getting resolved

Posted 24-Aug-21 2:59am

A B 8

Updated 24-Aug-21 7:03am

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CPallini · Answer 1 · 2021-08-24T03:41:00

There are some errors, in your code.
I show you how to perform insertion 'at start' (that is replacing the head, if I got you)

C

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

struct Node
{
  int data;
  struct Node *ptr;
};

void display_linkedList(struct Node *head)
{

  struct Node *temp = head;

  while ((temp->ptr) != head)
  {
    printf("ELEMENT IS %d \n", temp->data);
    temp = temp->ptr;
  }

  printf("ELEMENT IS %d \n", temp->data);
  // free(temp); ERROR!
}

struct Node *insertion_at_the_start(struct Node * head, int value)
{
  struct Node * new_node;
  new_node = (struct Node *) malloc(sizeof(struct Node )); //creation of new node 
  if ( ! new_node )
    return new_node; // handle possible malloc failure

  new_node->data = value;
  new_node->ptr = head;

  struct Node * next_node = head;

  while ( next_node->ptr != head)
    next_node = next_node->ptr;
  next_node->ptr = new_node;

  return new_node;
}


int main(int argc, char const *argv[])
{
  struct Node * head;
  struct Node *second;

  head = (struct Node *)malloc(sizeof(struct Node));

  second = (struct Node *)malloc(sizeof(struct Node));

  head->data = 1;
  head->ptr = second;

  second->data = 2;
  second->ptr = head;

  printf("\nORIGINAL CIRCULAR LINKED LIST IS ----------------------------------\n");
  display_linkedList(head);

  printf("\nCIRCULAR LINKED LIST AFTER INSERTION AT START IS ----------------------------------\n");

  head = insertion_at_the_start(head, 111111);
  display_linkedList(head);

  head = insertion_at_the_start(head, 222222);
  display_linkedList(head);

  return 0;
}

KarstenK · Answer 2 · 2021-08-24T07:03:00

Solution 2

There is a magic tool for helping you out: the debugger. Start learning Using the debugger tutorial and find your mistake.

Start with some polishing of your code by using indention and some output in critical code lines.

Posted 24-Aug-21 7:03am

KarstenK