//Part 2: Complete this method to evaluate Postfix Expressions using MyListStack
static int EvaluatePostFix(string[] stringItems, MyListStack stack)
{
// Cycle through string array for various operations
for (int i = 0; i < stringItems.Length; i++)
{
int temp;
bool isNumeric = int.TryParse(stringItems[i], out temp);
if (isNumeric) // if index is a number
{
stack.Push(temp);
}
else // if index is an operation
{
int first = stack.Pop();
int second = stack.Pop();
int total = 0;
// Switch for mathematic operations
switch (stringItems[i])
{
case "+":
total = first + second;
Console.Write("(" + first + " + " + second + ")\n");
stack.Push(total);
break;
case "-":
total = first - second;
Console.Write("(" + first + " - " + second + ")\n");
stack.Push(total);
break;
case "*":
total = first * second;
Console.Write("(" + first + " * " + second + ")\n");
stack.Push(total);
break;
case "/":
total = first / second;
Console.Write("(" + first + " / " + second + ")\n");
stack.Push(total);
break;
case "%":
total = first % second;
Console.Write("(" + first + " % " + second + ")\n");
stack.Push(total);
break;
} // switch
} // else
} // for
return(stack.Pop());
}
static void Main(string[] args)
{
MyListStack myStack = new MyListStack();
string testString = "56+2*1+";
// Create string array
string[] stringItems = new string[testString.Count()];
// Turn string into string array
for (int i = 0; i < testString.Length; i++)
{
stringItems[i] = testString[i].ToString();
}
//debugging
//for (int i = 0; i < stringItems.Length; i++)
//{
// Console.Write(stringItems[i]);
//}
// Output Format
Console.WriteLine("Stack Input:");
Console.WriteLine(testString);
Console.WriteLine("Press any key to calculate total...\n");
Console.ReadKey();
Console.WriteLine("Stack Output:");
// Run Instance
int result = EvaluatePostFix(stringItems, myStack);
// Output Format
Console.WriteLine("\nTotal: " + result);
Console.WriteLine("Press any key to close application.");
Console.ReadKey();
}
