For this assignment, start an array-based list implementation to track songs in a playlist.

Dont forget that list ADTs start at position 1, but the underlying array used in this class starts at position 0 like any C++ array.

Once youre comfortable with the code, you have two tasks:

void setEntry(int pos, const ItemType& item) 

Replace item at position pos in the list with the new parameter item. Throw the invalid_argument exception if pos < 1 or pos > getLength().

bool remove(int pos)

Remove the item at position pos. You need to update the state of the list, that is, shift items after pos over one to get rid of the gap left by the removed item and update numItems. If the remove operation is successful, return true. If it was not successful, for example because pos is out of range, return false.

Here is the code. #include  #include  #include  using namespace std; template class List { private: static const int CHUNK_SIZE=100; ItemType *list; int numItems; int maxItems; public: // default constructor and destructor List() { numItems = 0; maxItems = CHUNK_SIZE; list = new ItemType[CHUNK_SIZE]; } ~List() { delete [] list; } // list member functions bool isEmpty() const { return numItems==0; } int getLength() const { return numItems; } bool insert(int pos, const ItemType& item); bool remove(int pos); // clear the list // clear can simply set numItems to zero. The array list may still contain // items already inserted into the list, but since numItems is zero, there // isn't any way to get at them using getEntry() or setEntry() void clear() { numItems = 0; } // return entry at postion pos // throw invalid_argument if pos<1 or pos>getLength() ItemType getEntry(int pos) const; // set entry at postion pos to item // throw invalid_argument if pos<1 or pos>getLength() void setEntry(int pos, const ItemType& item); }; template bool List::insert(int pos, const ItemType& item) { bool canAdd; canAdd = ((pos > 0) && (pos <= numItems + 1) && (numItems < maxItems)); if (canAdd) { // first, we have to move everything after our insertion point over one // position to make room for our new item. start at the back of the list. // don't forget arrays start at postion zero and our list ADT starts at // position 1. for(int i=numItems; i>=pos; i--) list[i] = list[i-1]; // now put our item at position pos-1 list[pos-1] = item; numItems++; } return canAdd; } template ItemType List::getEntry(int pos) const { if(pos<1 || pos>getLength()) { throw invalid_argument("ERROR: getEntry() using invalid position"); } return list[pos-1]; } // TODO: add implementations for setEntry() and remove() functions // Utility function to input a track number with some input checking // to make sure it's a number int getTrack() { bool inputCheck; int trackNumber; do { inputCheck = true; cout << "Please enter the track number you'd like to view: "; if (!(cin >> trackNumber)) { cout << "Please enter numbers only. "; cin.clear(); cin.ignore(10000,' '); inputCheck = false; } } while (!inputCheck); return trackNumber; } int main() { List songs; char goAgain = 'y'; int trackNumber; string trackName; // Insert some songs into our list songs.insert(1, "One More Saturday Night"); songs.insert(1, "Friday I'm in Love"); songs.insert(3, "Sunday Morning Coming Down"); songs.insert(1, "California Love"); cout << "Welcome! There are " << songs.getLength() << " tracks. "; while (goAgain!='n') { trackNumber = getTrack(); try { trackName = songs.getEntry(trackNumber); } catch (invalid_argument arg) { cout << arg.what() << endl; trackName = "No Track"; } cout << "Your track name is " << trackName << endl; cout << "Go again? (y/n) "; cin >> goAgain; } cout << "Rock on! "; return 0; }