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LinkedList.cpp
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LinkedList.cpp
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#include "LinkedList.h"
//constructor
LinkedList::LinkedList()
{
length=0;
listData = NULL;
}
//destructor
LinkedList::~LinkedList()
{
MakeEmpty();
}
int LinkedList::GetLength() const
{
return length;
}
bool LinkedList::IsFull() const
{
NodeType* location;
try
{
location = new NodeType;
delete location;
return false;
}
catch (std::bad_alloc e)
{
return true;
}
}
bool LinkedList::IsEmpty() const
{
return (listData== NULL)? true: false;
}
void LinkedList::MakeEmpty()
{
NodeType *tempPtr;
while (listData != NULL)
{
tempPtr = listData;
listData = listData->next;
delete tempPtr;
}
length = 0;
listData = NULL;
}
// Pre: list is not full and item is not in list.
// Post: item is in the list; length has been incremented.
void LinkedList::InsertItem (char item )
{
NodeType * location;
// obtain and fill a node
location = new NodeType;
location->info = item;
location->next = listData;
listData = location;
length++;
}
// Pre: Key member of item is initialized.
// Post: If found, item�s key matches an element�s key in the list and a copy of that
// element has been stored in item; otherwise, item is unchanged.
void LinkedList::RetrieveItem(char& item, bool& found )
{
bool moreToSearch;
NodeType* location;
location = listData;
found = false ;
moreToSearch = ( location != NULL ) ;
while ( moreToSearch && !found )
{
if ( item == location->info) // match here
{
found = true;
item = location->info;
}
else // advance pointer
{
location = location->next;
moreToSearch = ( location != NULL );
}
}
}
//pre: item's key has been initialized. An element in the list has a key that matches item's
//Post: no element in the list has a key that matches item's
void LinkedList::DeleteItem(char item)
{
NodeType* location = listData;
NodeType* tempLocation;
// Find the item
if (item == listData->info)
{ // item in first location
tempLocation = location;
listData = listData->next; //move the head of the list
}
else{
//let location points to the node before the matching node
while (item != (location->next)->info)
location = location->next;
//remove the middle one, connect the two ends
tempLocation = location->next;
location->next = (location ->next)->next;
}
delete tempLocation;
length--;
}
void LinkedList::ResetList()
{
currentPos = NULL;
}
//Pre: the item at the current position is not the last in the list
//Post: current position has been updated. Item is current item. Does not check for running off the end of the lsit
void LinkedList::GetNextItem(char& item)
{
if (currentPos == NULL)
currentPos = listData;
else
currentPos = currentPos->next;
item = currentPos->info;
}
void LinkedList::PrintList(LinkedList& list)
// Pre: list has been initialized.
// Post: Each component in list has been written.
//
{
int length;
char item;
list.ResetList( );
length = list.GetLength( );
for (int counter = 1; counter <= length; counter++)
{
list.GetNextItem(item);
cout << item;
}
}