Question

Write a program in C++ that will make changes in the list of strings by modifying its last element.
Your program should have two functions:
1. To change the last element in the list in place. That means, without taking the last element from
the list and inserting a new element with the new value.
2. To compare, you need also to write a second function that will change the last element in the list
by removing it first, and inserting a new element with the new value.
The main creates the list, creates the string variables, populates few elements in the list (couple is
enough) and calls the functions to modify the list. After each call to the functions, the main should print
out the value of the last element in the list, so the changes are visible. Again, you print the last element
not from within the functions, but from the main.
Note 1: You will need to use references to implement the in-place requirement.
Note 2: However difficult that assignment may look like, all information you need on how to work with
the list is given to you in the lecture and both your functions implementation are just very few short
statements (hint: If you find yourself writing 5 or more lines of codes for each function, you probably
do it wrong).

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What i have so far, but keeps on getting an error once the functions are called.

// StringsList.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include "pch.h"
#include
#include
#include
#include
#include

using namespace std;

void funcWithList(list &, const std::string &);
void replacementForList(list &, const std::string &);

int main()
{
   ofstream out_data("Output.txt", ios::out);
   //end of copy code
   if (!out_data)
   {
       cout << "Error in opening the file, Output.txt";
       getchar();
       exit(1);

   }

std::cout << "Hello World!\n";

   list aList; //create list taking std::string
std::string input;

//get input to change last string

std::cin >> input;
   out_data << input;
   std::string s = input;

   //I can pass list to the function like that:
   funcWithList(aList, s);
   replacementForList(aList, s);

   getchar();
   out_data.close();//close output.txt file
   return 0;
}

void funcWithList(list &, const std::string &)
{
   ofstream out_data("Output.txt", ios::out);
   //end of copy code
   if (!out_data)
   {
       cout << "Error in opening the file, Output.txt";
       getchar();
       exit(1);

   }

   list tempList //myList.push_front;

   //I can access the last element like that:
   std::cout << "\nThe last element is: " << & tempList.back();

tempList.pop_back();  

std::string input;

//get input to change last string

std::cin >> input;
   out_data << input;
   std::string s = input;

   tempList.push_back(s);
}

void replacementForList(list &, const std::string &)
{
   ofstream out_data("Output.txt", ios::out);
   //end of copy code
   if (!out_data)
   {
       cout << "Error in opening the file, Output.txt";
       getchar();
       exit(1);

   }

   list tempList //myList.push_front;

   //I can access the last element like that:
   std::cout << "\nThe last element is: " << &tempList.back();

tempList.pop_back();  

std::string input;

//get input to change last string

std::cin >> input;
   out_data << input;
   std::string s = input;

   tempList.push_back(s);
}

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no examples or expected outputs were given but did state: "The main creates the list, creates the string variables, populates few elements in the list (a couple is
enough) and calls the functions to modify the list. After each call to the functions, the main should print
out the value of the last element in the list, so the changes are visible. Again, you print the last element
not from within the functions, but from the main."

therefore would look something like...

Fill your list with names...

Freddie

Nick

James

Rick

Now function calls

modify using references

what new name to use?

Robert

print from main, the last element

Robert

modify using deletion

what new name to use?

Tim

print from main, the last element

Tim

Answer 1

Code:

#include <list>
#include <string>
#include <iostream>

using namespace std;

void funcWithList(list<string> &, const std::string &);
void replacementForList(list<string> &, const std::string &);

int main()
{

   list<string> aList; //create list taking std::string

   aList.push_back("Freddie");
   aList.push_back("Nick");
   aList.push_back("James");
   aList.push_back("Rick");

   cout << "\nNames in the list\n";

   list<string>::iterator it = aList.begin();

   while (it != aList.end())
   {
       cout << "\n" << *it;
       it++;
   }

   cout << "\nNow function calls\n";
  
   std::string input;

   //get input to change last string

   cout << "\nModify using reference\n";
   cout << "\nWhat name to use?\n";

   std::cin >> input;
   std::string s = input;

   //I can pass list to the function like that:
   funcWithList(aList, s);

   cout << "\nPrint from main, Last Element :" << aList.back();

   cout << "\nModify using Deletion\n";
   cout << "\nWhat new name to use?\n";

   std::cin >> input;
   std::string s1 = input;

   replacementForList(aList, s1);

   cout << "\nPrint from main, Last Element :" << aList.back();

   getchar();
   return 0;
}

void funcWithList(list<string>& aList, const std::string & s)
{
   //In place Replacement
   aList.assign(aList.size() - 1, s);
}

void replacementForList(list<string>& a_list, const std::string & s)
{
   //Remove the last element and replace
   a_list.pop_back();
   a_list.push_back(s);
}

OUTPUT: