public double Begin()
{
Console.Write(_welcomeString);
for (; ;)
{
Console.Write(_promptString);
var userInput = Console.ReadLine();
if (userInput.Contains('?'))
{
Console.WriteLine(_helpString);
foreach (var key in MathematicalExpressionEvaluator.ExpressionEvaluators.Keys)
{
Console.Write("{0} ", key);
}
Console.WriteLine("\n");
}
var inputStatement = new MathematicalExpressionStatement(userInput);
double?answer = null;
foreach (var expression in inputStatement.Expressions)
{
if (MathematicalExpressionEvaluator.ExpressionEvaluators.ContainsKey(expression.Operator))
{
answer = MathematicalExpressionEvaluator.ExpressionEvaluators[expression.Operator](expression, answer);
}
else
{
Console.WriteLine(_errorString, expression.Operator);
answer = null;
break;
}
}
if (answer.HasValue)
{
Console.Write(_answerString, answer);
}
}
}
public void TwoNumberCalculations()
{
var userInput = "12 3 +";
var inputStatement = new MathematicalExpressionStatement(userInput);
double?answer = null;
foreach (var expression in inputStatement.Expressions)
{
if (MathematicalExpressionEvaluator.ExpressionEvaluators.ContainsKey(expression.Operator))
{
answer = MathematicalExpressionEvaluator.ExpressionEvaluators[expression.Operator](expression, answer);
}
else
{
answer = null;
break;
}
}
Assert.Equal("15", answer.ToString());
}
public void SriesOfAdditionsAndOrSubtractions()
{
var userInput = "12 34 + 56 + 78 - 90 + 12 -";
var inputStatement = new MathematicalExpressionStatement(userInput);
double?answer = null;
foreach (var expression in inputStatement.Expressions)
{
if (MathematicalExpressionEvaluator.ExpressionEvaluators.ContainsKey(expression.Operator))
{
answer = MathematicalExpressionEvaluator.ExpressionEvaluators[expression.Operator](expression, answer);
}
else
{
answer = null;
break;
}
}
Assert.Equal("102", answer.ToString());
}
