Exception when accessing a NULL pointer in linked list

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C++

debugging

Hello all,

I am developing a tool to read the data from a file and store in a linked list. I access the linked list and write the data into another file depending on some conditions.

The base structures needed for this operation are:

// Structure to store the data of an Element.
typedef struct ElemNode
{
    CString     szID;       // Stores the Element ID.
    WORD        wLength;    // Stores the Length of the 'Value' field.
    ValueType   eType;      // Stores the type of the 'Value' field.
    CString     szValue;    // Stores the Value of the Element.
    ElemNode    *pNextElem; // Pointer to the Next Element.
}ElemNode;

// Structure to store the data of an Item.
typedef struct ItemNode
{
    CString     szID;           // Stores the Element ID.
    WORD        wLength;        // Stores the Length of the 'Value' field.
    ValueType   eType;          // Stores the type of the 'Value' field.
    CString     szValue;        // Stores the Value of the Element.
    ElemNode    *pElemList;     // Pointer to the Element List of the particular Item.
    ItemNode    *pNextItem;     // Pointer to the Next Item.
}ItemNode;

The Linked list structure after reading the data is something like :

ItemNode -> ElemNode -> ElemNode -> ElemNode -> NULL
|
ItemNode -> NULL
|
ItemNode -> ElemNode -> ElemNode -> ElemNode ... (conatins 13 ElemNodes)
|
ItemNode -> ElemNode -> ... (contains 16 ElemNodes).
|
NULL

I need to access the szValue field of the 3rd ElemNode (shown in bold)in 1st ItemNode structure. I directly use the following statement.

ItemNode *pFirstItem;  // This points to the First ItemNode.
CString strTempString = pFirstItem->pElemList->pNextElem->pNextElem->szValue

If one of the ElemNode is missing, then this statement will cause the app to crash. I know of using UserException and throwing them. But the problem is, I can't go putting my own code to check for the NULL cases and throw the UserException.

Is there any way I can avoid the crash by throwing an exception? In other words, what is the exception thrown by the system in such cases?

I am using MFC and developing this tool in Visual-Studio 2005.
If there is any project related settings that is needed, please tell me.