SumOf5Numbers

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SumOfFiveNumbers
{
    class Program
    {
        static void Main(string[] args)
        {

    //write a program to add a sequence of numbers, inputted on one line, separated by space.
            string input = Console.ReadLine();
            double sum = 0.0; // this will keep our sum

            //loop over the input string, a string is an array of chars, and as an array we can iterate over it
            for (int i = 0; i < input.Length; i++)
            {
                //string to parse is declared in the for loop, so at every iteration it is empty again.
                string stringToParse = string.Empty;
                //if we are currently at a digit, we start going forward and collect all the digits
                if (char.IsDigit(input[i]) || input[i] == '-')
                {
                    //if the char is not whitespace, it is part of a number (digit or decimal point)
                    while (!char.IsWhiteSpace(input[i]))
                    {
                        //append the current char to the string
                        stringToParse += input[i];
                        //increment i, so after we exit from the while loop, the for loop continues at the same position
                        //the idea is that we don't collect the same digits again and again
                        //we have to test if we are at the end of the string! (indices are zero based)
                        if (i == input.Length - 1)
                        {
                            break;
                        }

                        i++;
                    }

                    //if the code enters the while loop and reaches this line, we now have to parse the string to a number and add it to a sum
                    // we can make sure by testing if stringToParse is not empty
                    if (stringToParse != string.Empty)
                    {
                        double number = double.Parse(stringToParse);
                        sum += number;
                    }
                }
            }

            Console.WriteLine(sum);
        }
    }
}