/// <summary>
/// 後序轉結果的演算過程
/// </summary>
/// <param name="postfix">後序</param>
/// <param name="stack">堆疊</param>
private static void ComputeIterative(List <string> postfix, Stack <decimal> stack)
{
foreach (var item in postfix)
{
//判斷是不是單元或雙元運算子
bool isBinary = OperatorController.GetInstance().GetBinaryMarks().Contains(item);
bool isUnary = OperatorController.GetInstance().GetUnaryMarks().Contains(item);
if (IsNumber(item))
{
stack.Push(decimal.Parse(item));
}
else if (isBinary)
{
//防呆
if (stack.Count < 2)
{
throw new Exception("後序有誤");
}
//計算
decimal number1 = stack.Pop();
decimal number2 = stack.Pop();
stack.Push(BinaryCompute(item, number2, number1));
}
else if (isUnary)
{
//防呆
if (stack.Count < 1)
{
throw new Exception("後序有誤");
}
//計算
decimal number = stack.Pop();
stack.Push(UnaryCompute(item, number));
}
else
{
Console.WriteLine($"item = {item}");
throw new Exception("無法識別的符號");
}
}
}
/// <summary>
/// 中序轉後序的演算法
/// </summary>
/// <param name="infix">中序</param>
/// <param name="result">結果</param>
/// <param name="stack">堆疊</param>
private void ComputeIterative(List <string> infix, List <string> result, Stack <string> stack)
{
foreach (var item in infix)
{
if (IsNumber(item))
{
result.Add(item);
}
else if (item.Equals("("))
{
stack.Push(item);
}
else if (item.Equals(")"))
{
while (stack.Count > 0 &&
!stack.Peek().Equals("("))
{
result.Add(stack.Pop());
}
//無效運算式
if (stack.Count > 0 &&
!stack.Peek().Equals("("))
{
throw new Exception("無效運算式");
}
else
{
stack.Pop();
}
}
else
{
//限定成既有的運算符號。若輸入了未定義運算符會error
while (stack.Count > 0 &&
OperatorController.GetInstance().GetPriority(item) <= OperatorController.GetInstance().GetPriority(stack.Peek()))
{
result.Add(stack.Pop());
}
stack.Push(item);
}
}
}
/// <summary>
/// 單元運算
/// </summary>
/// <param name="op">運算規則的名稱</param>
/// <param name="number">數字</param>
/// <returns>運算結果</returns>
private static decimal UnaryCompute(string op, decimal number)
{
var formula = OperatorController.GetInstance().GetUnaryFormula(op);
return(formula(number));
}
