How to do input validation and draw a table?

Question

C++ / C#

Good evening!
Tell me how to check that an integer is entered, and not a fractional or a letter? At the moment, when you enter something that is not a whole program crashes.
And how to draw a table so that there is text inside it in the center with indents along the edges and the width of the table depends on the entered text with a limit on the number of characters?
I'm stuck for now. Guide me please.

Draft code

using System;

namespace ConsoleApp_HW03
{
    class Program
    {
        static void Main(string[] args)
    {
      while (true)
      {
        Console.Write("Введите размерность таблицы: ");

        var table = Console.ReadLine();
        var number = int.Parse(table);

        if (number % 2 == 0 && number <= 6)

        {
          Console.Write($"Введите произвольный текст: ");
          string text;
          while ((text = Console.ReadLine()) != string.Empty)
          {
            switch (text.Length)
            {
              case <= 40:
                Console.WriteLine("В яблочко!");
                break;
              case > 40:
                Console.Write("Перелет. Попробуйте снова: ");
                break;

            }
          }
        }

        else
                {
                    Console.WriteLine($"Неприемлимое значение. Попробуйте еще раз.");
                }

            }
    }
  }
}

Answer 1

https://docs.microsoft.com/ru-ru/dotnet/api/system...

Answer 2

Regular \d+