Question

C++ program, inventory.cpp implementation

Mostly need the int load(istream&) function.

Implementation: You are supposed to write three classes, called Item, Node and Inventory respectively Item is a plain data class with item id, name, price and quantity information accompanied by getters and setters Node is a plain linked list node class with Item pointer and next pointer (with getters/setters) Inventory is an inventory database class that provides basic linked list operations, delete load from file / formatted print functionalities. The majority of implementation will be done in this class as well as find / add / The following diagram illustrates the data structure maintained by your Inventory class: Inventory Node Item head id item 30001 DietCoke next name price 1.99 35 quantity item id 30002 CokeZero next name price 1.98 32 quantity item id 40001 Milk1Gal next name price 2.49 _quantity 30 nullptr The top left corner of the above figure shows the only private data member of the Inventory class: _head, a pointer to the first node in the linked list. The value is nullptr if the list is empty. Just to the right of these two data members is a column (in blue) of list nodes linked. Each node of the (singly) linked list has a next field, and an item field storing a pointer to an Item object. The Item object that the item field of each node points to are displayed (in green) to the right. The types of the four fields are int, string, double, and int, respectively For all nodes in the list except the last node, the next field of the node at position pos will point to the next node. Thenext field of the last node will point to nullptr Note that the order of the items is last-come-first-out. That is, the most recently added node is at the head. We do not manage a tail pointer this time Files you will submit: stockmgmt.cpp item.h contains your main function contains the Item class declaration contains the Item class member function definitions contains the Node/Inventory class declaration contains the Node/Inventory class member function definitions item.cpp inventory.h inventory.cpp Points to the first node in the list Will be nullptr if the list is empty. head: Node Private Public Inventory( Inventory(O void push_front ( Item* ) Initializeshead to nullptr. Free up (i.e., delete) all nodes in the list. Allocate a new Node with the parameter item, then insert it at the front of the list. Update_head to the new Node pointer. Returns the first item of the list (i.e., head's item). If there is no Node, return nullptr. Public Public Inventory Item* front () const Public bool pop_front() Public Deletes the first node. Return true if the delete was successful, false otherwise (i.e., no node) Public int stockIn(const int, const int) Find an item with the given id (first parameter), then increase its quantity by the given value (second parameter). Return the updated quantity. If there is no item with the given id, return -1 Find an item with the given id (first parameter), then decrease its quantity by the given value (second parameter) If the given value is greater than the current quantity in stock, update the quantity as zero. Return how many items are withdrawn. (For example, if there was 20 in stock and 30 was asked, the updated quantity is 0 and 20 is returned.) Add a new item to the inventory, if there is no item with the same ID. Return true if the addition was successful. False Public int stockOut (const int, const int) addNewItem ( Item*) bool Public otherwise, that is, there is already an item with the same ID. Find an item with the given ID, then delete it. IMPORTANT] How to delete an item (1) Find the node with the item with the given ID (say A) (2) Switch A's item and head's item (3) Delete head (using pop head) Returns true if there are no nodes in the list, false bool delete Item Public const int) bool isEmpty () const otherwise. (Hint: check if head is nullptr) Reads records from an istream, and insert them to the inventory. Each line has the four fields for one item record Per record, an Item object is allocated and added to the inventory. Returns the number of records read. Note: There is no corrupt data. No validation needed Note 2: still, you need to check if there is a duplicate id. Note 3: Use addNewItem function int load(istream&)

Answer 1

int load(istream & s){
   std::string line = "";
   std::string word = "";
   int count = 0;
   while(s){
       s.getline(line);
       stringstream ss(line);
       Item *i = new Item();
       ss>>word;
       int id = std::stoi(word);
       i->setId(id);
       word = "";
       ss>>word;
       i->setName(word);
       word = "";
       ss>>word;
       double price = std::stod(word);
       i->setPrice(price);
       word = "";
       ss>>word;
       int q = std::stoi(word);
       i->setQuantity(q);
       line = "";
       if(!addNewItem(i)){   //if duplicate id present add its quantity.
           stockIn(i->getID(),i->getQuantity());
       }
       count++;
   }
   return count;
}