# Flavors of while loops

- Write a `while` loop asking the user for an integer, and looping as long as that integer is stricly greater than 0.
- Transform your `while` loop so that the program displays the sum of all the numbers entered when exiting the `while` loop.

An example of execution could be:

    Enter a positive number to sum, or a negative number to exit
    12
    Enter a positive number to sum, or a negative number to exit
    3
    Enter a positive number to sum, or a negative number to exit
    -2
    Your total is 15.

Identify what type of loop it is: is it user-controlled, counter-controlled, or sentinel-controlled? Does it use a counter, a sentinel value, or an accumulator?

# TryParse Method

## Getting Familiar With It

Consider the code we just studied:

    Console.WriteLine("Please, enter an integer.");
    string message = Console.ReadLine();
    int a;
    bool res = int.TryParse(message, out a);
    if (res)
        {
            Console.WriteLine($"The value entered was an integer: {a}.");
        }
    else
        {
            Console.WriteLine("The value entered was not an integer, so 0 is assigned to a.");
        }
    Console.WriteLine(a);

What happen if:

- The user enters an integer?
- The user enters a floating-point value?
- The user enters nothing?
- The user enters a string that contains alphabetical characters?

## Using It

1. Write a code that ask the user to enter an integer, and ask the user again as long as the user entered something that isn’t an integer.
2. Actually, there is a `TryParse` method in other classes as well: there is for instance a `Double.TryParse` and a `Decimal.TryParse` method. Write a small program that uses one of them.