SwitchCase语句中的TryParse

Question

I'm making a calculator, and I'm using a switch-case statement to determine what to do when the user clicks a button. When the user just presses a number (0-9) then I want to simply just add the number to the end of the current string. This was an easy task, although I was wondering if there's an easier way to evaluate if a string is a number in a case statement.

In other words, can I simplify the following:

case "0":
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":

//code to execute here

I know I can call TryParse earlier on and run a separate block of code, but I was wondering if there was a way to do something such as case myString.TryParse():

Thanks.

Answer 1

You are definitely going the long way around when there are simple libraries already able to handle this :)

try System.Char.IsDigit(numericChar)

There are many other ways to do this easily, just google around for a bit :)

Answer 2

You can give it a try to use pattern matching , but I think specifying as in original post should be much faster, so I don't recommend it, but you can in fact do what you asked:

string a = "5";
switch (a)
{
   case var digit when char.IsDigit(a[0]):
     var intDigit = int.Parse(digit);
     ...
     break;
   ...
   <other cases>
}

Answer 3

Switch statements aren't suited for looking for multiple possible values, you would be better of with a bunch of if else statements

if(Char.IsDigit(inputString))
{

}
else if(someCondition)
{
}
else if(someCondition2)
{
}