リンクされたリストのサイズ機能？

Question

ここに私は問題があると思うサイズ関数では、基本的に削除前と削除後にリンクされたリスト全体のサイズを持たせたいのですが、サイズ関数は "サイズが返さなければなりません"というエラーを返します。 ！助けを応援!!おかげ

//SLL Basic insert , delete and search functions 

#include<iostream> 
using namespace std; 

/* defines the structure of a single linked list node*/ 
typedef struct list_node { 
    int data; 
    struct list_node *next; // pointer to next node in the list 
}node; 

/* create new node */ 
node *getNewNode(int data) { 
    node *new_node = new node; 
    new_node->data = data; 
    new_node->next = NULL; 
    return new_node; 
} 

/* get size of list */ 
node* size(node *head) 
{ 
    int len = 0; 
    while (head != NULL) 
    { 
     len++; 
     head = head->next; 

    } 
    return len; 
} 

/* displays the list elements */ 
void displayList(node *head) { 
    cout << "Displaying List : "; 
    while (head != NULL) { 
     cout << head->data << " -> "; 
     head = head->next; 
    } 
    cout << "NULL " << endl; 
} 

/* Search the node with element as data 
Return the pointer to the node if found else return NULL */ 
node *searchNode(node *head, int data) { 
    node *ptr = NULL; 
    while (head) { 
     if (head->data == data) { 
      ptr = head; 
      break; 
     } 
     head = head->next; 
    } 
    return ptr; 
} 

/* insert a node at the beginning of the list */ 
node *insertNodeBeg(node *head, int data) { 
    node *ptr = getNewNode(data); 
    if (head == NULL) { // if list is empty 
     head = ptr; 
    } 
    else { 
     ptr->next = head; 
     head = ptr; 
    } 
    return head; 
} 

/* insert a node at the end of the list */ 
node *insertNodeEnd(node *head, int data) { 
    node *ptr = getNewNode(data); 
    if (head == NULL) { //if list is empty 
     head = ptr; 
    } 
    else { 
     node *temp = head; 
     while (temp->next != NULL) { // move to the last node 
      temp = temp->next; 
     } 
     temp->next = ptr; // insert node at the end 
    } 
    return head; 
} 

/* insert a node at the after a particular node in the list */ 
node *insertNodeAfter(node *head, int element, int data) { 
    // search the element after which node is to be inserted 
    node *temp = searchNode(head, element); 
    if (temp == NULL) { // element not found 
     cout << "Element not found ... " << endl; 
    } 
    else { 
     node *ptr = getNewNode(data); 
     if (temp->next == NULL) { // node has to inserted after the last node 
      temp->next = ptr; 
     } 
     else { // insert the node after the first or an intermediate node 
      ptr->next = temp->next; 
      temp->next = ptr; 
     } 
    } 
    return head; 
} 

/* delete a particular node from the list */ 
node *deleteNode(node *head, int element) { 
    node *temp = searchNode(head, element); // search the node to be deleted 
    if (temp == NULL) { // element not found 
     cout << "Node to be deleted not found ... " << endl; 
    } 
    else { 
     if (temp == head) { // first node is to be deleted 
      head = head->next; 
      delete temp; 
     } 
     else { // node to deleted is an intermediate or last node 
      node *ptr = head; 
      while (ptr->next != temp) { 
       ptr = ptr->next; 
      } 
      ptr->next = temp->next; 
      delete temp; 
     } 
    } 
    return head; 
} 

int main() 
{ 
    node *head = NULL; 
    head = insertNodeBeg(head, 7);  // 7 
    head = insertNodeBeg(head, 9);  // 9 -> 7 
    head = insertNodeEnd(head, 11);  // 9 -> 7 -> 11 
    head = insertNodeAfter(head, 9, 4); // 9 -> 4 -> 7 -> 11 
    head = insertNodeAfter(head, 7, 3); // 9 -> 4 -> 7 -> 3 -> 11 
    head = insertNodeAfter(head, 11, 6); // 9 -> 4 -> 7 -> 3 -> 11 -> 6 
    head = size(head);// HERE i want to give size of LIST i,e 6 in this case !! 
    displayList(head); 
    head = deleteNode(head, 7);   // 9 -> 4 -> 3 -> 11 -> 6 
    head = deleteNode(head, 6);   // 9 -> 4 -> 3 -> 11 
    head = deleteNode(head, 9);   // 4 -> 3 -> 11 
    head = deleteNode(head, 3);   // 4 -> 11 
    displayList(head); 
    return 0; 
} 

Answer 1

声明return len;はint len = 0;によって宣言されたint型を返すですが、あなたの関数の定義は、ノード構造体へのポインタを返すことを期待され、node* size(node *head)です。 node* size(...)をint size(...)

Answer 2

"node *"ではなく "int"にします。あるいは、符号なしの整数値でなければならないのでsize_tにしてください。

/* get size of list */ 
    size_t size(node *head) 
    { 
     size_t len = 0; 
     while (head != NULL) 
     { 
      len++; 
      head = head->next; 
     } 
     return len; 
    }