C++ inventory item removal - c++

Question

Increase the inventory to be 10 items. DONE!!!
Create a for loop that asks the user to input the initial items in the inventory.DONE!!!
After the for loop create a minor story where the healer changes two items (i.e. items 4 and 8).What I want is to SWAP an item for another item ie would you like to trade your {[item] for [item2] y or n
Sort the inventory in alphabetical order. You can use your own sort if you want, but here is a bubble sort algorithm:
// A simple inventory program using a struct to store data
// in an array.
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <sstream>
using namespace std;
// define a data structure
struct InventoryRecord
{
string name; // inventory item name
int qty; // how many are in stock
double value; // the value
};
// const for the max size of the record array
const int MAX_SIZE = 9;
// function prototypes
void addData(InventoryRecord list[], int& size);
void dispData(const InventoryRecord list[], int size);
void remData( const InventoryRecord list[], int size);
void saveFile(const InventoryRecord list[], int size);
void openFile(InventoryRecord list[], int& size);
char getMenuResponse();
int main(int argc, char *argv[])
{
InventoryRecord recList[MAX_SIZE];
int numOfRecs = 0;
bool run = true;
do
{
cout << "Hero's Inventory - " << numOfRecs << " items in your bag" << endl;
switch ( getMenuResponse() )
{
case 'A': addData(recList, numOfRecs); break;
case 'D': dispData(recList, numOfRecs); break;
case 'R': remData(recList, numOfRecs); break;
case 'O': openFile(recList, numOfRecs); break;
case 'S': saveFile(recList, numOfRecs); break;
case 'Q': run = false; break;
default : cout << "That is NOT a valid choice" << endl;
}
} while (run);
cout << endl << "Program Terminated" << endl;
// system("PAUSE"); // Program exits immediatly upon "Quit" if commented out
return EXIT_SUCCESS;
}
// Task: Allow data entry of one inventory item
// Accepts: References to the inventory array and its size
// Returns: Nothing
// Modifies: The array and size 'actual parameter'
// NOTE: Could be modified to allow entry of more than one item
void addData(InventoryRecord list[], int& size)
{
InventoryRecord tmp; // declare a temp item that we will load before putting in the array
char response;
char str[256]; // needed for cin.getline; we are going to use a char array
if (size < MAX_SIZE) {
system("cls");
cout << "Please enter 10 items helpful to your quest! " << endl;
cout << "Enter item: " << endl << endl;
cout << "Name: ";
// Get up to 256 characters from the keyboard including white space.
// Stop reading if encounter the \n first. If there's any chance of
// more than 256 characters you will have to clean up cin with
// cin.ignore before the next input.
cin.getline(str, 256, '\n'); // for char arrays; different from the other getline
tmp.name = str;
cout << "Quantity: ";
cin >> tmp.qty;
cout << "Value: ";
cin >> tmp.value;
cout << endl;
// see if this record should be added to the array
cout << "Add to inventory? (y/n) ";
cin >> response;
if (toupper(response) == 'Y')
list[size++] = tmp;
} else {
cout << "Inventory is full; cannot enter more units." << endl;
system("pause");
}
system("cls");
}
void dispData(const InventoryRecord list[], int size)
{
system("cls");
double cost = 0;
if(size < 1) {
cout << "Nothing to display" << endl;
} else {
cout << "All Items in your Bag" << endl << endl;
cout << fixed << setprecision(2);
cout << "Item Name Qty Value" << endl;
cout << "~~~~~~~~~~~~~~~~~~" << endl;
cout << left;
for (int i = 0; i < size; i++) {
cout << setw(21) << list[i].name << right
<< setw(4) << list[i].qty
<< setw(10) << list[i].value << left << endl;
cost = cost + list[i].value * list[i].qty;
}
cout << "~~~~~~~~~~~~~~~~~~~" << endl;
cout << right << setw(3) << size;
cout << " items listed";
cout << right << setw(19) << cost << endl << endl;
}
system("PAUSE");
system("cls");
}
void remData(const InventoryRecord list[], int size) {
system("cls");
cout <<"Enter Item you wish to remove from your inventory: " << endl;// This is being displayed so user can see items in the inventory
double cost = 0;
if(size < 1) {
cout << "Nothing to display" << endl;
} else {
cout << "All Items in your Bag" << endl << endl;
cout << fixed << setprecision(2);
cout << "Item Name Qty Value" << endl;// It is not displaying right the alignment is off
cout << "~~~~~~~~~~~~~~~~~~" << endl;
cout <<"Item Name: ";/* from here I do not know what to do! What I want is have use type the item name they want removed
also display an error if they enter an item wrong*/
cout << left;
for (int i = 0; i < size; i++) {
cout << setw(21) << list[i].name << right
<< setw(4) << list[i].qty
<< setw(10) << list[i].value << left << endl;
cost = cost + list[i].value * list[i].qty;
}
cout << "~~~~~~~~~~~~~~~~~~~" << endl;
cout << right << setw(3) << size;
cout << " items listed";
cout << right << setw(19) << cost << endl << endl;
}}
// Save records to disc
void saveFile(const InventoryRecord list[], int size) {
ofstream outfi("Inventory.txt");
// make sure the file stream is open before doing IO
if (!outfi.fail()) {
system("cls");
cout << "Saving inventory to the disc ";
for(int i = 0; i < size; i++) {
outfi << list[i].name << ';'
<< list[i].qty << ';'
<< list[i].value;
// Start a new line after all but the last record
// Simplifies reading the file as EOF is at end of last line
if (i < size-1) outfi << endl;
}
cout << endl << size << " records writen to the disc." << endl;
outfi.close();
system("PAUSE");
system("cls");
}
else {
cout << "ERROR: problem with file" << endl;
system("PAUSE");
system("cls");
}
}
// Open file and load array
void openFile(InventoryRecord list[], int& size)
{
ifstream infi("Inventory.txt");
string str;
stringstream strstrm;
// make sure the file stream is open before doing IO
if (!infi.fail()) {
system("cls");
cout << "Reading inventory from the disc ";
size = 0; // overwrite any existing records
while(!infi.eof() && size < MAX_SIZE) {
// get and store the name
getline(infi, str, ';');
list[size].name = str;
// get, convert and store the quantity
getline(infi, str, ';');
strstrm.str(""); strstrm.clear(); // empty and clear the stringstream
strstrm << str;
strstrm >> list[size].qty;
// get, convert and store the cost
getline(infi, str);
strstrm.str(""); strstrm.clear(); // empty and clear the stringstream
strstrm << str;
strstrm >> list[size++].value;
}
cout << endl << size << " records read from the disc." << endl;
system("PAUSE");
system("cls");
}
else { // something went wrong with opening the file
cout << "ERROR: problem with file" << endl;
system("PAUSE");
system("cls");
}
}
char getMenuResponse()
// Task: Put the menu on screen and get a response
// Accepts: Nothing
// Returns: The users response
// Modifies: Nothing
// NOTE: Characters are far more intuitive at the command
// line than numbers; avoid using numbers.
{
char response;
cout << endl << "Make your selection" << endl
<< "(A)dd Items, (D)isplay Items, (R)emove items, (O)pen File, (S)ave File, (Q)uit" << endl
<< "> ";
cin >> response;
cin.ignore(256, '\n');
// clean-up up to 256 chars including the delimiter specified (\n, the endl)
// OR stop when the \n is encountered after removing it.
return toupper(response);
}

Answer 1

To remove an element from your inventory, you just need to move all elements after the removed element one position forward. Once that is done, you also need to reduce the lengthy by one. For example, to remove the elements at the position index from an array array with currently length elements you could use
if (index < length) {
std::copy(array + index + 1, array + length, array + index);
++length;
}

Answer 2

There are essentially two ways to remove the element, the easiest is swap the element which you want to delete with the last one and resize the list:
void deleteElem(Data[] list, int & listLength, int ix) {
if (ix < listLength - 1) {
list[ix] = list[listLength - 1];
}
--listLength;
}
The second solution is memmove everthing after the to deleting element one to the left:
void deleteElem(Data[] list, int & listLength, int ix) {
memmove(list[ix], list[ix + 1], (listLength - ix - 1) * sizeof(Data));
--listLength;
}
EDIT: There was an error in the length for memmove, always the same. You should read the documentation.