C rotate linked list by user choice - c

Question

I wrote a program that get from a user numbers to linked list and number for how much to rotate each node in lust for the left. and I was only succeeded to do that but not in a circle. and my program need to be abale to move the node more left then the lenght of the list in circles.
someone know how can i fix my program??. (the function that need to be fixed is the "RotateALinkedList" function). i mean if the user want to move the list 4 times left the first node gonna start from the last node.
#include<stdio.h>
#include<stdlib.h>
typedef struct numbers_list
{
int data;
struct numbers_list* next;
}number;
void RotateALinkedList(number** head, int node); //the function that rotate the linked list
int CreateLinkedList(number** head, int iNumberofNode);
int attachToEnd(number** head, int k);
void PrintTheList(number* pNode);
void FreeAllocatedMemory(number** head);
int main(void)
{
int list_len = 0;
int data = 0;
number* head = NULL;
printf("How many nodes in list? ");
scanf("%d", &list_len);
getchar();
CreateLinkedList(&head, list_len);
printf("Choose a number k, and the list will be rotated k places to the left: ");
scanf("%d", &data);
getchar();
if (data <= list_len)
{
RotateALinkedList(&head, data);
PrintTheList(head);
}
else
{
printf("Please Enter Valid number of node\n");
}
FreeAllocatedMemory(&head);
getchar();
return 0;
}
void RotateALinkedList(number** head, int node)
{
int count = 0;
number* p = *head;
number* tempNode = NULL;
for (count = 1; ((count < node) && (p != NULL)); count++)
{
p = p->next;
}
if (p == NULL)
{
return;
}
else
{
tempNode = p;
}
while (p->next != NULL)
{
p = p->next;
}
p->next = *head;
*head = tempNode->next;
tempNode->next = NULL;
}
int CreateLinkedList(number** head, int iNumberofNode)
{
int data = 0;
int iRetValue = -1;
int count = 0;
number* pNewNode = NULL;
for (count = 0; count < iNumberofNode; count++)
{
printf("Enter number: ");
scanf("%d", &data);
getchar();
if ((*head) == NULL)
{
pNewNode = (number*)malloc(sizeof(number));
if (pNewNode != NULL)
{
pNewNode->data = data;
pNewNode->next = NULL;
*head = pNewNode;
iRetValue = 0;
}
}
else
{
iRetValue = attachToEnd(head, data);
}
}
return iRetValue;
}
int attachToEnd(number** head, int k)
{
int iRetValue = -1;
number* pLastNode = NULL;
number* pNewNode = NULL;
pLastNode = *head;
pNewNode = (number*)malloc(sizeof(number));
if (pNewNode != NULL)
{
pNewNode->data = k;
pNewNode->next = NULL;
iRetValue = 0;
}
if (pLastNode == NULL)
{
*head = pNewNode;
}
else
{
while (pLastNode->next != NULL)
{
pLastNode = pLastNode->next;
}
pLastNode->next = pNewNode;
}
return iRetValue;
}
void PrintTheList(number* pNode)
{
printf("the rotated list:\n");
while (pNode != NULL)
{
printf("%d ", pNode->data);
pNode = pNode->next;
}
}
void FreeAllocatedMemory(number** head)
{
number* ptempNode = NULL;
number* pFirstNode = NULL;
pFirstNode = *head;
while (pFirstNode != NULL)
{
ptempNode = pFirstNode;
pFirstNode = pFirstNode->next;
free(ptempNode);
}
*head = NULL;
}

Answer 1

For starters the name number of the alias in this typedef declaration
typedef struct numbers_list
{
int data;
struct numbers_list* next;
}number;
is confusing.
It will be better to define two structures instead
struct Node
{
int data;
struct Node *next;
};
struct List
{
size_t size;
struct Node *head;
};
and define in main a list like
struct List numbers = { .size = 0, .head = NULL };
You will simplify your task if the list contains a data member that specifies the number of nodes in the list.
The function CreateLinkedList should do one task: create a list from an array specified by the user. It should ask the user to enter numbers that will be stored in the list.
I can suggest the following solution shown in the demonstrative program below.
#include <stdio.h>
#include <stdlib.h>
struct Node
{
int data;
struct Node *next;
};
struct List
{
size_t size;
struct Node *head;
};
void clear( struct List *list )
{
while ( list->head )
{
struct Node *tmp = list->head;
list->head = list->head->next;
free( tmp );
}
list->size = 0;
}
size_t create( struct List *list, const int a[], size_t n )
{
clear( list );
for ( struct Node **current = &list->head;
n-- && ( *current = malloc( sizeof( struct Node ) ) ) != NULL; )
{
( *current )->data = *a++;
( *current )->next = NULL;
current = &( *current )->next;
++list->size;
}
return list->size;
}
FILE * display( const struct List *list, FILE *fp )
{
fprintf( fp, "There is/are %zu items: ", list->size );
for ( struct Node *current = list->head; current != NULL; current = current->next )
{
fprintf( fp, "%d -> ", current->data );
}
fputs( "null", fp );
return fp;
}
void rotate( struct List *list, size_t n )
{
if ( ( list->size != 0 ) && ( ( n %= list->size ) != 0 ) )
{
struct Node **current = &list->head;
while ( n-- ) current = &( *current )->next;
struct Node *tmp = list->head;
list->head = *current;
*current = NULL;
struct Node *last = list->head;
while ( last->next != NULL ) last = last->next;
last->next = tmp;
}
}
int main(void)
{
struct List numbers = { .size = 0, .head = NULL };
int a[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
create( &numbers, a, sizeof( a ) / sizeof( *a ) );
fputc( '\n', display( &numbers, stdout ) );
rotate( &numbers, 1 );
fputc( '\n', display( &numbers, stdout ) );
rotate( &numbers, 2 );
fputc( '\n', display( &numbers, stdout ) );
rotate( &numbers, 3 );
fputc( '\n', display( &numbers, stdout ) );
rotate( &numbers, 4 );
fputc( '\n', display( &numbers, stdout ) );
clear( &numbers );
return 0;
}
The program output is
There is/are 10 items: 0 -> 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> null
There is/are 10 items: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0 -> null
There is/are 10 items: 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0 -> 1 -> 2 -> null
There is/are 10 items: 6 -> 7 -> 8 -> 9 -> 0 -> 1 -> 2 -> 3 -> 4 -> 5 -> null
There is/are 10 items: 0 -> 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> null