how to update individual elements in this OOP case? - c++

Question

I have this "movie store.cpp"
#include "List.h"
#include <iomanip>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <cmath>
using namespace std;
//****************************************************************************************************
const static char* FILE_NAME = "Movies.csv";
int totalCheckedIn1 = 0;
int totalCheckedOut1 = 0;
//****************************************************************************************************
struct Movie
{
int MPAC;
int year;
int runtime;
int checkedIn;
int checkedOut;
string title;
Movie()
{
}
Movie(int m, int y, int r, int ci, int co, string t)
{
MPAC = m;
year = y;
runtime = r;
checkedIn = ci;
checkedOut = co;
title = t;
}
bool operator == (const Movie& rhs) const
{
return (MPAC == rhs.MPAC);
}
Movie& operator =(const Movie& rhs)
{
MPAC = rhs.MPAC;
year = rhs.year;
runtime = rhs.runtime;
checkedIn = rhs.checkedIn;
checkedOut = rhs.checkedOut;
title = rhs.title;
return *this;
}
friend ostream& operator <<(ostream& os, const Movie& m);
};
void setInventory(List<Movie> z, double f)
{
}
//****************************************************************************************************
ostream& operator<<(ostream& os, const Movie& m)
{
os << setw(7) << left << m.MPAC
<< setw(25) << left << m.title
<< setw(7) << left << m.year
<< setw(10) << left << m.runtime
<< setw(7) << left << m.checkedIn
<< setw(7) << left << m.checkedOut;
return os;
}
//****************************************************************************************************
void getData(List<Movie>& Movies);
void displayList(List<Movie>& Movies);
void findMovies(List<Movie> Movies);
//****************************************************************************************************
int main()
{
List<Movie> WebsterMovies;
getData(WebsterMovies);
cout << "CHECK";
displayList(WebsterMovies);
// findMovies(WebsterMovies);
setInventory(WebsterMovies, 10.5);
cout << "The following data is the updated Webster Movies store\n";
//displayList(WebsterMovies);
system("PAUSE");
return 0;
}
//****************************************************************************************************
void getData(List<Movie>& Movies)
{
ifstream infile(FILE_NAME);
if (!infile)
{
cout << "Problem opening file" << endl;
exit(99);
}
while (!infile.eof())
{
Movie m;
if (infile.peek() == EOF)
break;
infile >> m.MPAC;
infile.ignore();
infile >> m.year;
infile.ignore();
infile >> m.runtime;
infile.ignore();
infile >> m.checkedIn;
infile.ignore();
infile >> m.checkedOut;
infile.ignore();
getline(infile, m.title);
Movies.insert(m);
}
infile.close();
}
//****************************************************************************************************
void displayList(List<Movie>& Movies)
{
int totalCheckedIn = 0;
int totalCheckedOut = 0;
cout << "The Webster Movie Store list includes : " << endl;
cout << setw(7) << left << "MPAC"
<< setw(25) << left << "Title"
<< setw(7) << left << "Year"
<< setw(10) << left << "RunTime"
<< setw(7) << left << "In"
<< setw(7) << left << "Out" << endl;
cout << "-------------------------------------------------------------------------------" << endl;
double totalRunTime = 0;
for (int i = 0, size = Movies.getNumber();
i < size; ++i)
{
Movie m = Movies.getNext();
cout << m << endl;
totalRunTime += m.runtime;
totalCheckedIn += m.checkedIn;
totalCheckedOut += m.checkedOut;
}
cout << "The average run time for the " << Movies.getNumber()
<< " movies is " << fixed << setprecision(1)
<< totalRunTime / Movies.getNumber() << endl;
cout << "There are " << totalCheckedIn << " movies checked in " << endl;
cout << "There are " << totalCheckedOut << " movies checked out" << endl;
totalCheckedIn1 = totalCheckedIn;
}
//****************************************************************************************************
void findMovies(List<Movie> Movies)
{
while (true)
{
cout << "Enter the MPAC of a movie to locate:";
int input;
cin >> input;
if (input == 0)
break;
Movie m;
m.MPAC = input;
if (Movies.getMember(m))
{
cout << setw(7) << left << "MPAC"
<< setw(25) << left << "Title"
<< setw(7) << left << "Year"
<< setw(10) << left << "RunTime"
<< setw(7) << left << "In"
<< setw(7) << left << "Out" << endl;
cout << "-------------------------------------------------------------------------------" << endl;
cout << m << endl;
}
else
{
cout << "That movie is not in the store" << endl;
}
}
}
this is "list.h"
#ifndef LIST_H
#define LIST_H
#include <iostream>
//********************************************************************************
template <typename T>
class List
{
public:
List();
List(int size);
List(const List &obj);
~List();
void insert(T);
T getNext(); // Returns the next element in the array.
bool getMember(T&); // Returns true if we can find the member, false otherwise.
int getNumber(); // Returns the number of items in the list.
private:
T *pList;
int numberInList; // Number of elements in the list.
int listSize; // Size of the list.
int nextIndex; // Index that points to the next element in the array.
};
//********************************************************************************
// Default Constructor
template <typename T>
List<T>::List()
{
numberInList = 0;
listSize = 100;
nextIndex = 0;
pList = new T[listSize];
}
//********************************************************************************
// Overloaded Constructor
template <typename T>
List<T>::List(int size)
{
numberInList = 0;
listSize = size;
nextIndex = 0;
pList = new T[listSize];
}
//********************************************************************************
// Copy Constructor
template <typename T>
List<T>::List(const List &obj)
{
numberInList = obj.numberInList;
listSize = obj.listSize;
nextIndex = obj.nextIndex;
pList = new T[listSize];
for (int i = 0; i < listSize; i++)
{
pList[i] = obj.pList[i];
}
}
//********************************************************************************
// Destructor
template <typename T>
List<T>::~List()
{
delete[]pList;
}
//********************************************************************************
template <typename T>
void List<T>::insert(T item)
{
int temp = numberInList++;
pList[temp] = item;
}
//********************************************************************************
template <typename T>
T List<T>::getNext()
{
return pList[nextIndex++];
}
//********************************************************************************
template <typename T>
bool List<T>::getMember(T& item)
{
for (int i = 0; i < numberInList; ++i)
{
if (item == pList[i])
{
item = pList[i];
return true;
}
}
return false;
}
//********************************************************************************
template <typename T>
int List<T>::getNumber()
{
return numberInList;
}
#endif
Problem i have is that setInventory function needs to update the checkedIn member of each list element using the formula (CheckedIn + CheckedOut) * ( f /100.0). Can someone guide me how can i update individual element using this function.help i got said" In order to update each element of the List, you need modify the template to include a setItem function that sets the associated element in the List object to the item that is passed to the setItem function. HINT: This function should only contain one C++ statement."
if someone can guide me syntax of how i can update individual elements.
this is something i wrote for setInventory()
void setInventory(List<Movie> WebsterMovies , double f)
{
Movie m = WebsterMovies.getNext();
cout << m << endl;
cout << "Check again" << endl << endl;
int size = WebsterMovies.getNumber();
int increment = 0;
for (int i = 0 ; i < size; ++i)
{
cout << m << endl;
increment = trunc(((m.checkedIn + m.checkedOut) * f )/ 100);
m.checkedIn = m.checkedIn + increment;
cout << "updated checkin is : " << m.checkedIn << endl;
WebsterMovies.setItem(m);
Movie m = WebsterMovies.getNext();
}
}
this is setItem i wrote
template <typename T>
void List<T>::setItem(T item)
{
pList[numberInList] = item;
}
p.s beginner here so sorry for bad English or any other mistake.

Answer 1

To update an element in a container, such as std::list, you need to find the element, then update the fields.
An example:
std::list<Movie> database;
// Search by title
std::list<Movie>::iterator iter;
const std::list<Movie>::iterator end_iter = database.end();
for (iter = database.begin();
iter != end_iter;
++iter)
{
if (iter->title == search_title)
{
Update_Movie(*iter);
}
}