using System;

using System.Collections.Generic;

using System.Globalization;

using System.Text;

​

public class Program

{

    // Define valid numerical characters including digits, minus sign, and decimal point

    private static readonly char[] validNumericalValues = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '.' };

​

    public static List<double> ExtractNumbers(string input)

    {

        var numbers = new List<double>();

        var currentNumber = new StringBuilder();

        bool isInsideNumber = false;

​

        foreach (var character in input)

        {

            if (IsValidNumericalValue(character))

            {

                currentNumber.Append(character);

                isInsideNumber = true;

            }

            else if (isInsideNumber)

            {

                AddNumberToList(currentNumber.ToString(), numbers);

                currentNumber.Clear();

                isInsideNumber = false;

            }

        }

​

        if (currentNumber.Length > 0)

        {

            AddNumberToList(currentNumber.ToString(), numbers);

        }

​

        return numbers;

    }

​

    private static bool IsValidNumericalValue(char character) => Array.IndexOf(validNumericalValues, character) != -1;

​

    private static void AddNumberToList(string numberString, ICollection<double> numbers)

    {

        if (double.TryParse(numberString, NumberStyles.Any, CultureInfo.InvariantCulture, out double number))

        {

            numbers.Add(number);

        }

    }

​

    static void Main()

    {

        string inputString = "The price is $42.75 for two items and $18.50 for one item.";

        var extractedNumbers = ExtractNumbers(inputString);

        Console.WriteLine("Extracted Numbers:");

        foreach (var number in extractedNumbers)

        {

            Console.WriteLine(number);

        }

    }

}

​