C# CMD input validation

Question

I'm trying to make it so that when a number is entered my program will not crash, which this does so far. Then I want it to re ask for an input until the correct charcter type is enetered.

int firstNum;
int Operation = 0;

   switch(Operation)
   {
        case 1:
            bool firstNumBool = int.TryParse(Console.ReadLine(), out firstNum);
         break;
   }

You would need to wrap your logic in a loop, I would suggest a while loop on each execution of the loop, check if the Console.ReadLine() value is equal to the character and if so, terminate the loop — Ryan Wilson
– Ryan Wilson, Commented Nov 14, 2018 at 13:29
@RyanWilson I get I need some sort of loop but idk how to code it, like while (firstNum != int) { int.tryparse(Console.readline())? — Ryan W
– Ryan W, Commented Nov 14, 2018 at 13:31

Dmitrii Bychenko · Accepted Answer · 2018-11-14 13:46:52Z

2

Decompose your solution; extract a method for inputing an integer:

 private static int ReadInteger(string title) {
   // Keep on asking until correct input is provided
   while (true) {
     if (!string.IsNullOrWhiteSpace(title))
       Console.WriteLine(title);

     if (int.TryParse(Console.ReadLine(), out int result))
       return result;

     Console.WriteLine("Sorry, not a valid integer value; please, try again.");
   }
 }

And then use it:

 int firstNum;

 ...

 switch(Operation)
 {
      case 1:
          firstNum = ReadInteger("First number");
          break;

      ...

edited Nov 14, 2018 at 13:46

answered Nov 14, 2018 at 13:33

Dmitrii Bychenko

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