public static void PrintQuestion(this SubtractionProblem sp, int questionNumber)
{
switch (sp.MissingPart)
{
case SubtractionProblemPart.Minuend:
Console.WriteLine($"({questionNumber}) _ - {sp.Subtrahend} = {sp.Difference}");
break;
case SubtractionProblemPart.Subtrahend:
Console.WriteLine($"({questionNumber}) {sp.Minuend} - _ = {sp.Difference}");
break;
default:
throw new ArgumentOutOfRangeException(paramName: nameof(sp.MissingPart), message: $"Missing Part is '{sp.MissingPart}'.");
}
}
public override object GenerateQuestion(Difficulty difficulty)
{
SubtractionProblem problem = new SubtractionProblem();
Random rand = new Random();
int[] easy = { 1, 15 };
int[] medium = { 15, 50 };
int[] hard = { 50, 1000 };
switch (difficulty)
{
case Difficulty.Easy:
problem.Minuend = rand.Next(easy[0], easy[1]);
problem.Subtrahend = rand.Next(easy[0], problem.Minuend);
problem.Difference = problem.Minuend - problem.Subtrahend;
break;
case Difficulty.Medium:
problem.Minuend = rand.Next(medium[0], medium[1]);
problem.Subtrahend = rand.Next(medium[0], problem.Minuend);
problem.Difference = problem.Minuend - problem.Subtrahend;
break;
case Difficulty.Hard:
problem.Minuend = rand.Next(hard[0], hard[1]);
problem.Subtrahend = rand.Next(hard[0], problem.Minuend);
problem.Difference = problem.Minuend - problem.Subtrahend;
break;
}
switch (rand.Next(2))
{
case 0:
problem.MissingPart = SubtractionProblemPart.Minuend;
break;
case 1:
problem.MissingPart = SubtractionProblemPart.Subtrahend;
break;
default:
throw new Exception("Missing part generated was not valid.");
}
return(problem);
}
public override bool IsCorrect(object problem, int answer)
{
SubtractionProblem p = (SubtractionProblem)problem;
switch (p.MissingPart)
{
case SubtractionProblemPart.Minuend:
return(p.Minuend == answer);
case SubtractionProblemPart.Subtrahend:
return(p.Subtrahend == answer);
case SubtractionProblemPart.Difference:
return(p.Difference == answer);
default:
return(false);
}
}
public static void AskSubtractionQuestions(Generator generator)
{
Subtract subject = new Subtract();
var questionCount = generator.QuestionCount;
var currentQuestion = 1;
while (currentQuestion <= questionCount)
{
SubtractionProblem p = (SubtractionProblem)subject.GenerateQuestion(generator.Difficulty);
var isCorrect = false;
while (!isCorrect)
{
// Ask question
p.PrintQuestion(currentQuestion);
// Get answer
Console.Write("Answer: ");
int answer = 0;
bool validAnswer = true;
try
{
answer = Convert.ToInt32(Console.ReadLine());
}
catch (Exception)
{
validAnswer = false;
}
// Work out if answer is correct
if (validAnswer)
{
isCorrect = subject.IsCorrect(p, answer);
Console.WriteLine(isCorrect ? "Correct!" : "Not quite right. Try again.");
}
}
currentQuestion++;
}
}
