Pointing to the last element and ending of program

Been working on some C++ exercises and what I’m doing is finding out the 5 number summary(max, min, q1,q2,q3) and the number of inputted ints for a group of integers that are inputted. This is an extension of an exercise for Accelerated C++. There are a few things that I’m unsure of. Firstly how do to refer to the last element if I don’t know how many elements there are in the vector. It also shows the results once you input the ints that you want to have in and then end-of-file. How do you end-of-file in a program. I’ve tried pressing the end button but it doesn’t work. Also I have used one and two as the 1st and 3rd quartile respectively. Have I done the right thing, if not, why not and how would you do it. Thanks for the help.:)

Code:

`#include<algorithm>`

#include<iomanip>

#include<ios>

#include<iostream>

#include<string>

#include<vector>

using namespace std;

int main()

{

cout<<"Please input your numbers:";

vector<int> numbers;

int number;

while(cin>>number)

numbers.push_back(number);

typedef vector<int>::size_type numbersize;

numbersize size=numbers.size();

if(size==0){

cout<<endl<<"You must enter your numbers"<<endl;

return 1;

}

//sort the grades

sort(numbers.begin(),numbers.end());

//computer the median homework grade

numbersize mid=size/2;

double median;

median= size % 2 ==0 ? (numbers[mid] +numbers[mid-1])/2

: numbers[mid];

numbersize one= mid/2;

numbersize two=mid + one;

cout<<"The median is: "<<median;

cout<<"The 1st quartile is: "<< one;

cout<<"The 3rd quartile is: "<<two;

cout<<"The min value is: "<<numbers[0];

cout<<"There are "<<numbers.size()<<" elements that you inputted";

}