void Start()
{
int choice = 0;
decimal d1 = 0;
decimal d2 = 0;
var validChoices = new int[] { 1, 2, 3, 4, 5 };
var firstPrompt = "\n\nChoose Calc type \r\n1. Add\r\n2. Subtract\r\n3. Multiply\r\n4. Divide\r\n5. Exit\r\nSelection: ";
var firstNumberPrompt = "Enter first decimal: \r\n";
var secondNumberPrompt = "Enter second decimal: \r\n";
do
{
Console.WriteLine(firstPrompt);
choice = int.Parse(Console.ReadLine());
if (choice != 5 && validChoices.Contains(choice))
{
d1 = GetDecimalInput(firstNumberPrompt);
d2 = GetDecimalInput(secondNumberPrompt);
}
switch (choice)
{
case 1:
Console.WriteLine($"the result is: {Calc.Add(d1, d2)}");
break;
case 2:
Console.WriteLine($"the result is: {Calc.Subract(d1, d2)}");
break;
case 3:
Console.WriteLine($"the result is: {Calc.Multiply(d1, d2)}");
break;
case 4:
Console.WriteLine($"the result is: {Calc.Divide(d1, d2)}");
break;
case 5:
choice = 99;
break;
default:
Console.WriteLine("Invalid Selection: \r\n");
break;
}
} while (validChoices.Contains(choice));
Console.ReadLine();
}