When the user entera a non number into a integer variable the stream will fail. Look at line 19 in your code that should give you a idea what to do.
I would also suggest reading up on how streams work in C++ since they are very handy to know about.
Here is a quick example
using namespace std;
int sum = 0;
cout << "Enter your numbers or a non number to stop!" << endl;
// The condition is saying keep the loop running
// until cin >> number is not true. So since when we
// enter anything but a number into a integer the stream break
// the condition will be false since we are no longer able to read
// numbers into the variable.
while (cin >> number)
sum += number;
cout << sum << endl;
You are also going to have to take a look at how you want your program to run again. Remember that you will need to find the max number entered, min number enters and the means.
What I do is before I start to code anything I grab a notepad or go into a text editor and write down all the requirements of my program. So your would look like this
1) Find sum
2) Find max
3) Find min
I then write down anything I will need to do that requirement, or any ideas I have for it. Like this.
1) Find sum: Need to have a variable to store the sum of all the numbers in. When inputting the numbers just += the inputted number to sum IE (sum += number).
2) Find max: Need a variable to hold the largest number entered. To find this largest number I need conditional operators to compare all the numbers entered so far.
For large projects its also good to break the problem down into little managable problems and then make a plan of how to go through it like this.
Problem: Get each students name, age, and grade from their test. Then find the median of the students grades.
1) Create a class type that will be used for each student.
2) Get input from the user about each student. I'm going to use a vector<Student> to hold all of the students
3) Sort the vector<Student> by their grades. Use the std::sort() function
4) Find the median of the grades.
Now obviously that is a very simplified version of it but it shows how it can help. That way before I every start coding I know exactly what I need to do step by step, what variables I will need and the tools I need. So I go in with a plan which makes it much easier to solve each problem.