Have this outline for a singly linked list program need to figure out how to write the code for the InsertItem, FreeNodes and DisplayList functions in c++

#include

#include

#include

#include

using namespace std;

// linked list structure

struct LNode

{

int item;

LNode *next;

};

// function prototypes

int DisplayList(const LNode *head);

void DisplayMenu();

void FlushInstream(istream &inStream = cin);

int FreeNodes(LNode *head);

LNode* InsertItem(LNode *head, int index, int item, bool &bSuccess);

// ==== main ==================================================================

//

// ============================================================================

int main()

{

bool bLoop = true;

bool bResult;

char selection;

int index;

int intVal;

int numInts = 0;

LNode *headPtr = NULL;

// allow the user to manipulate the list

do {

// display the main menu

DisplayMenu();

// get the user selection

cout << " Please enter your selection: ";

cin >> selection;

// call the appropriate member function

switch (toupper(selection))

{

case 'A':

// get a new integer value to insert

cout << "Please enter a value to insert: ";

if (!(cin >> intVal))

{

cout << "Error reading int, please try again... ";

FlushInstream();

continue;

}

// get an index

cout << "Please enter a target index: ";

if (!(cin >> index))

{

cout << "Error reading int, please try again... ";

FlushInstream();

}

else if ((index > numInts) || (index < 0))

{

cout << "Index is out of range... ";

continue;

}

else

{

headPtr = InsertItem(headPtr, index, intVal, bResult);

if (false == bResult)

{

cout << "Sorry, insertion failed... ";

}

else

{

++numInts;

}

}

break;

case 'C':

// release all nodes in the list

if (NULL == headPtr)

{

cout << "List is currently empty." << endl;

}

else

{

numInts = FreeNodes(headPtr);

cout << numInts;

cout << " item";

cout << ((1 == numInts) ? " " : "s ");

cout << "released." << endl;

headPtr = NULL;

numInts = 0;

}

break;

case 'D':

// display the current contents of the list

if (NULL == headPtr)

{

cout << "List is currently empty." << endl;

}

else

{

cout << "Here is the list:" << endl;

DisplayList(headPtr);

cout << "There ";

cout << ((1 == numInts) ? "is " : "are ");

cout << numInts << " item";

cout << ((1 == numInts) ? "" : "s");

cout << " in the list" << endl;

}

break;

case 'Q':

bLoop = false;

numInts = FreeNodes(headPtr);

cout << numInts;

cout << " item";

cout << ((1 == numInts) ? " " : "s ");

cout << "released. Bye!" << endl;

break;

default:

cout << "Unrecognized response; try again... ";

break;

} // end of switch

} while (true == bLoop);

return 0;

} // end of "main"

// ==== DisplayMenu ===========================================================

//

// This function displays the menu selections to stdout.

//

// Input:

// Nothing.

//

// Output:

// Nothing.

//

// ============================================================================

void DisplayMenu()

{

cout << " Do you wish to: ";

cout << " A)dd a new item to the list ";

cout << " D)isplay the current contents of the list ";

cout << " C)lear the list ";

cout << " Q)uit the program ";

} // end of "DisplayMenu"

// ==== DisplayList ===========================================================

//

// This function displays the current contents of the list to stdout.

//

// Input:

// head [IN] -- a pointer to the head of the linked list

//

// Output:

// The number of items written to stdout.

//

// ============================================================================

int DisplayList(const LNode *head)

{

??

} // end of "DisplayList"

// Input:

// inStream -- a reference to the input stream to flush

//

// Output:

// Nothing.

//

// ============================================================================

void FlushInstream(istream &inStream)

{

char inChar;

inStream.clear();

while (false == inStream.eof())

{

inStream.get(inChar);

if (' ' == inChar)

{

break;

}

}

} // end of "FlushInstream"

// ==== FreeNodes =============================================================

//

// This function traverses the linked list and releases the memory allocated

// for each individual node.

//

// Input:

// head -- a pointer to the head of the linked list

//

// Output:

// The total number of nodes released is returned.

//

// ============================================================================

int FreeNodes(LNode *head)

{

???

} // end of "FreeNodes"

// ==== InsertItem ============================================================

//

// This function inserts a new item into the list. If the item is inserted

// successfully, the boolean parameter is set to true, otherwise it is set to

// false.

//

// Input:

// head [IN] -- a pointer to the first node in the linked list

//

// index [IN] -- the zero-based location index for the new item

//

// item [IN] -- the integer value to insert into the list

//

// bSuccess [OUT] -- the boolean result of the insert operation (true

// if successful, false if not)

//

// Output:

// A pointer to the (potentially new) head of the linked list.

//

// ============================================================================

LNode* InsertItem(LNode *head, int index, int item, bool &bSuccess)

{

??

} // end of "InsertItem"