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PO
primarykey
Id
20187274
data
AcceptedAnswerId
0
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0
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0
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CreationDate
2013-11-25T07:55:03.350
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0
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2013-11-25T07:55:03.350
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0
OwnerUserId
3012015
ParentId
20184293
PostTypeId
2
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2
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0
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text
Body
The issue is with the way how double pointers are used. Here is the full working code: I have made some changes on the way how double pointers were used. You can see the changes in pop function and copyList function. <pre><code>#include <stdio.h> #include <stdlib.h> struct node { int data; struct node* next; }; static int length(struct node** head); static void push(struct node** head, int data); static int pop(struct node** head); static void appendNode(struct node** head, int data); static struct node *copyList(struct node** head); static void printList(struct node** head); /************************************************************ length - return length of a list ************************************************************/ int length(struct node** head) { int count = 0; struct node* current = NULL; current = *head; while (current != NULL) { current = current->next; ++count; } return count; } /************************************************************ push - add new node at beginning of list ************************************************************/ void push(struct node** head, int data) { struct node* new_ptr = NULL; new_ptr = (struct node*)malloc(sizeof(struct node)); new_ptr->data = data; new_ptr->next = *head; *head = new_ptr; } /************************************************************ pop - delete node at beginning of non-empty list and return its data ************************************************************/ int pop(struct node** head) { int val = 0; struct node* temp = NULL; if (*head != NULL) { val = (*head)->data; temp = (*head)->next; free(*head); *head = temp; } return(val); } /************************************************************ appendNode - add new node at end of list ************************************************************/ void appendNode(struct node** head, int data) { struct node* current = NULL; struct node* previous = NULL; struct node* new_ptr = NULL; current = *head; previous = current; while (current != NULL) { previous = current; current = current->next; } new_ptr = (struct node*)malloc(sizeof(struct node)); new_ptr->data = data; new_ptr->next = NULL; previous = new_ptr; } /************************************************************ copyList - return new copy of list ************************************************************/ struct node* copyList(struct node** head) { struct node* copy = NULL; struct node* current = NULL; struct node* new_ptr = NULL; /* Copy current head to copy */ current = *head; while (current != NULL) { appendNode(&copy, current->data); current = current->next; } return copy; } /************************************************************ printList - print linked list as "List: < 2, 5, 6 >" (example) ************************************************************/ void printList(struct node** head) { struct node* current = NULL; printf("List: < "); current = *head; if (current == NULL) printf("none "); while (current != NULL) { printf("%d", current->data); current = current->next; if (current != NULL) printf(", "); } printf(" >\n"); } void main() { int i; // index used for loops struct node *list_a; // a new list struct node *list_a_copy; // copy of list list_a = NULL; // initialize empty list list_a_copy = NULL; // initialize empy list // test push for (i = 0; i < 4; ++i) push(&list_a, i); // test length printf("Length of list = %d\n", length(&list_a)); // test print head list printf("head:\n"); printList(&list_a); // test append node for (i = 4; i < 8; ++i) appendNode(&list_a, i); // test print head list printf("head(append):\n"); printList(&list_a); // make a copy of list list_a_copy = copyList(&list_a); // test pop head list for (i = 0; i < 4; ++i) printf("%d popped\n", pop(&list_a)); // test print copy list printf("head copy:\n"); printList(&list_a_copy); // test pop copy list for (i = 0; i < 4; ++i) printf("%d popped\n", pop(&list_a_copy)); } </code></pre>
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1. This table or related slice is empty.
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1. POPointers Linked Lists C
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1. PTAnswer
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1. USbigyanshr
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1. VO
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2. VO
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