VS2019 C6011 Error Dereferencing Null Pointer 'NewNode'

Hello? I'm studying Doubly Linked List

Anyway, when I used to put data on node, there were C6011 error [:Dereferencing Null Pointer 'NewNode']

So I refered https://learn.microsoft.com/ko-kr/visualstudio/code-quality/c6011?view=vs-2019 and

tried to check null value. But It didn't work..

I checked some details on error window like picture I added

They said 'NewNode will be NULL', 'NewNode will be still NULL even if it is dereferenced'

Code is like below

1.header file(DoubleLinkedList.h)

#pragma once #ifndef DOUBLY_LINKEDLIST_H #define DOUBLY_LINKEDLIST_H #include <stdio.h> #include <stdlib.h> #include <malloc.h> typedef int ElementType; typedef struct MyNode { ElementType Data; struct MyNode* Prev; struct MyNode* Next; }Node; Node* DLL_CreateNode(ElementType NewData); //1.create node void DLL_DestroyNode(Node* Node);//2.destroy node void DLL_AppendNode(Node** Head, Node* NewNode);//3.append node /* 4.insert node connect prev-insert-next */ void DLL_InsertAfter(Node* Current, Node* NewNode); void DLL_RemoveNode(Node** Head, Node* Remove);//5.remove node Node* DLL_GetNodeAt(Node* Head, int location);//6.search node int DLL_GetNodeCount(Node* Head);//7.count the number of nodes #endif

2.DLL.cpp(which is for header file)

#include "DoubleLinkedList.h" Node* DLL_CreateNode(ElementType NewData) { //create node with memory allocation Node* NewNode = (Node*)malloc(sizeof(Node)); //nullptr check for c6011(https://learn.microsoft.com/ko-kr/visualstudio/code-quality/c6011?) if (NewNode) { NewNode->Data = NewData; NewNode->Prev = NULL; NewNode->Next = NULL; } return NewNode; } void DLL_DestroyNode(Node* Node) { free(Node); } void DLL_AppendNode(Node** Head, Node* NewNode) { if ((*Head) == NULL) { *Head = NewNode; } else { Node* Tail = (*Head); while (Tail->Next != NULL) { Tail = Tail->Next; } Tail->Next = NewNode; NewNode->Prev = Tail; } } void DLL_InsertAfter(Node* Current, Node* NewNode) { NewNode->Prev = Current->Next; NewNode->Next = Current; if (Current->Next != NULL) { Current->Next->Prev = NewNode; Current->Next = NewNode; } } void DLL_RemoveNode(Node** Head, Node* Remove) { if (*Head == Remove) { *Head = Remove->Next; if (*Head != NULL) { (*Head)->Prev = NULL; } Remove->Next = NULL; Remove->Prev = NULL; } else { Node* Temp = Remove; if (Remove->Prev != NULL) { Remove->Prev->Next = Temp->Next; } if (Remove->Next != NULL) { Remove->Next->Prev = Temp->Prev; } Remove->Prev = NULL; Remove->Next = NULL; } } Node* DLL_GetNodeAt(Node* Head, int location) { Node* Current = Head; while (Current != NULL && (--location) >= 0) { //--location >=0 is for check index Current = Current->Next; } return Current; } int DLL_GetNodeCount(Node* Head) { int count = 0; Node* Current = Head; while (Current != NULL) { Current = Current->Next; count++; } return count; }

3.Practice file(.c)

#include "DoubleLinkedList.h" int main() { int i = 0; int Count = 0; Node* List = NULL; Node* Current = NULL; Node* NewNode = NULL; //create&append nodes for (i = 0; i < 5; i++) { NewNode = DLL_CreateNode(i); DLL_AppendNode(&List, NewNode); } Count = DLL_GetNodeCount(List); for (i = 0; i < Count; i++) { Current = DLL_GetNodeAt(List, i); printf("List[%d] : %d\n", i, Current->Data); } Current = DLL_GetNodeAt(List, 2); NewNode = DLL_CreateNode(3000); DLL_InsertAfter(Current, NewNode); Count = DLL_GetNodeCount(List); for (i = 0; i < Count; i++) { Current = DLL_GetNodeAt(List, i); printf("List[%d] : %d\n", i, Current->Data); } for (i = 0; i < Count; i++) { Current = DLL_GetNodeAt(List, 0); if (Current != NULL) { DLL_RemoveNode(&List, Current); DLL_DestroyNode(Current); } } return 0; }

Thank you!