/// <summary>
/// Prompts the user for the coefficients of a polynomial, and sets the
/// the coefficientList field of the object.
/// The isValidPolynomial method is used to check for the validity
/// of the polynomial entered by the user, otherwise the field must
/// not change.
/// The acceptable format of the coefficients received from the user is
/// a series of numbers (one for each coefficient) separated by spaces.
/// All coefficients values must be entered even those that are zero.
/// </summary>
/// <returns>True if the polynomial is succeffully set, false otherwise.</returns>
public bool SetPolynomial()
{
//instruction Statement.
Console.WriteLine("\nEnter all coefficients for the polynomial seperted by a space (descending order).\nExample: Enter 2 0 3.5 -2 0 for the polynomial (2)*x^4 + (3.5)*x^2 + (-2)*x");
//Converts the input to a char array in order to use DigitReader method from the Arithmatic class.
string input = Console.ReadLine();
char[] arr = input.ToCharArray();
//checks for validity, and allows overwriting the set polynomolial.
if (IsValidPolynomial(input) && input.Length != 0)
{
coefficientList.Clear();
}
else
{
return(false);
}
for (int index = 0; index < arr.Length; index++)
{
if (arr[index].Equals('-') && Char.IsDigit(arr[index + 1]) && (index == 0 || !char.IsDigit(arr[index - 1])))
{
index++;
coefficientList.Add(-Arithmetic.DigitReader(arr, ref index));
}
else if (Char.IsDigit(arr[index]))
{
coefficientList.Add(Arithmetic.DigitReader(arr, ref index));
}
else if (!char.IsWhiteSpace(arr[index]))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Checks if the passed polynomial string is valid.
/// The acceptable format of the coefficient string is a series of
/// numbers (one for each coefficient) separated by spaces.
/// </summary>
/// <example>
/// Examples of valid strings: "2 3.5 0 ", or "-2 -3.5 0 0"
/// Examples of invalid strings: "3..5", or "2x^2+1", or "a b c", or "3 - 5"
/// </example>
/// <param name="polynomial">
/// A string containing the coefficient of a polynomial. The first value is the
/// highest order, and all coefficients exist (even 0's).
/// </param>
/// <returns>True if a valid polynomial, false otherwise.</returns>
public bool IsValidPolynomial(string polynomial)
{
char[] arr = polynomial.ToCharArray();
for (int index = 0; index < arr.Length; index++)
{
//DigitReader is used although the return is not save because of its reference index function.
if (arr[index].Equals('-') && Char.IsDigit(arr[index + 1]) && (index == 0 || !char.IsDigit(arr[index - 1])))
{
index++;
Arithmetic.DigitReader(arr, ref index);
}
else if (Char.IsDigit(arr[index]))
{
Arithmetic.DigitReader(arr, ref index);
}
else if (!char.IsWhiteSpace(arr[index]))
{
return(false);
}
}
return(true);
}
static void Main()
{
Calculus calculator = new Calculus();
Console.WriteLine("Welcome to the calculator program! Select from the menu:");
while (true)
{
Console.WriteLine();
Console.Write("(a)rithmetic, (s)et polynomial, (g)et all roots, (p)rint polynomial, (d)ifferentiate, (i)ntegrate, (q)uit? ");
string choice;
try
{
choice = Console.ReadLine().Trim().ToLower();
}
catch (System.IO.IOException e)
{
Console.WriteLine($"IO Exception: {e.Message}");
continue;
}
string result = string.Empty;
const double accuracy = 0.000001; //For simplcity, accuracy is set to a constant.
if (choice.StartsWith("a"))
{
result = Arithmetic.BasicArithmetic();
}
else if (choice.StartsWith("d"))
{
result = Derivative(calculator);
}
else if (choice.StartsWith("i"))
{
result = Integral(calculator);
}
else if (choice.StartsWith("g"))
{
try
{
List <double> roots = calculator.GetAllRoots(accuracy);
if (roots.Count == 0)
{
result = "No real roots found.";
}
else
{
for (int i = 0; i < roots.Count; i++)
{
result += $"root{i} = {roots[i]}\n";
}
}
}
catch (InvalidOperationException e)
{
result = e.Message;
}
}
else if (choice.StartsWith("p"))
{
try
{
result = calculator.GetPolynomial();
}
catch (InvalidOperationException e)
{
result = e.Message;
}
}
else if (choice.StartsWith("q"))
{
break;
}
else if (choice.StartsWith("s"))
{
if (calculator.SetPolynomial())
{
result = $"Polynomial saved successfully: {calculator.GetPolynomial()}";
}
else
{
result = "Not a valid polynomial.";
}
}
else
{
result = "Please choose from the menu";
}
Console.WriteLine();
Console.WriteLine(result);
}
}