6-4. Modify the movie list so it is now a set of movies. After the sentinel loop

Question

6-4.    Modify the movie list so it is now a set of movies. After the sentinel loop to fill up the set, let the user insert or delete by movie name (but do a check to see if it is already in the set (the elements must be unique for the insert). The set will already be sorted, but then use the copy & iterator to print on the screen.

The following is ex6-4a.cpp with comments showing the missing lines of code. Fill in the missing lines of code for part b - ex6-4b.cpp.

/*
Exercise 6-4a
This program will create a movie set
*/
#include<iostream>
#include<set>
#include<string>
#include<iterator>
#include<algorithm>
using namespace std;

void main()
{
    string name;.
    int ans, pos;
    bool found = false;
            // declare set of strings vm
      // declare set iterator vmit
        // declare iterator to cout osit
      // declare pair of set of string iterator named p

    cout << "Enter movie name (-1 to end): ";
    getline(cin, name, ' ');
    while (name != "-1")
    {
            // insert name into set, assign to pair object
                    // if pair's second field is true
                // print that pair's first field was inserted
        else
             // print that pairs' first field was already in set
        cout << "Enter movie name (-1 to end): ";
        getline(cin, name, ' ');
    }

    cout << "Enter 1 to insert, 2 to delete: ";
    cin >> ans;
    if (ans == 1)
    {
        cout << "Enter movie name: ";
        cin.ignore(1, ' ');
        getline(cin, name, ' ');

            // insert name into set, assign to pair object
                    // if pair's second field is true
                // print that pair's first field was inserted
        else
             // print that pairs' first field was already in set
    }
    else if (ans == 2)
    {
        cout << "Enter movie name to delete: ";
        cin.ignore(1, ' ');
        getline(cin, name, ' ');
            // find name in set, return to iterator
            // if iterator is not at the end of set
        {
             // print what iterator is pointing at to say will be deleted
             // delete that name from set
        }
        else
            cout << name << " not in set ";
    }

    cout << "Number of movies in set is " // print size
            // copy set to cout iterator
}

Explanation / Answer

/*
Exercise 6-4a
This program will create a movie set
*/
#include<iostream>
#include<set>
#include<string>
#include<iterator>
#include<algorithm>
using namespace std;

int main()
{
    string name;
    int ans, pos;
    bool found = false;
    std::set<std::string> movieSet;
    std::set<std::string>::iterator strIt;
    std::pair<std::set<std::string>::iterator,bool> strRet;

    std::cout << "Enter movie name (-1 to end): ";
    getline(cin, name, ' ');
    while (name != "-1")
    {

        // insert name into set, assign to pair object
        strRet = movieSet.insert(name);

        // if pair's second field is true
        // print that pair's first field was inserted
        if (strRet.second==true) {
            std::cout << name << " was inserted" << endl;   
        }
        else{
            // print that pairs' first field was already in set
            std::cout << name << " was already in set" << endl;
         }
        std::cout << "Enter movie name (-1 to end): ";
        getline(cin, name, ' ');
    }

    std::cout << "Enter 1 to insert, 2 to delete: ";
    std::cin >> ans;
    if (ans == 1)
    {
        std::cout << "Enter movie name: ";
        std::cin.ignore(1, ' ');
        getline(cin, name, ' ');

        // insert name into set, assign to pair object
        strRet = movieSet.insert(name);
      
        // if pair's second field is true
        // print that pair's first field was inserted
        if (strRet.second==true) {
            std::cout << name << " was inserted" << endl;  
        } else {
            // print that pairs' first field was already in set
            std::cout << name << " was already in set" << endl;
        }
    }
    else if (ans == 2)
    {
        std::cout << "Enter movie name to delete: ";
        cin.ignore(1, ' ');
        getline(cin, name, ' ');
      
        // find name in set, return to iterator
        strIt = movieSet.find(name);
      
        // if iterator is not at the end of set
        if(strIt != movieSet.end())
        {
            // print what iterator is pointing at to say will be deleted
            std::cout << name << " will be deleted" << endl;
            // delete that name from set
            movieSet.erase(strIt);
        }
        else
            std::cout << name << " not in set ";
    }
    // copy set to cout iterator
    std::cout << "Number of movies in set is " << movieSet.size() << endl; // print size
    for(strIt = movieSet.begin(); strIt != movieSet.end(); ++strIt)
    {
        std::cout << ' ' << *strIt;
    }
    std::cout << ' ';
}

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