SRP

srp.cs

using System;

namespace SolidRules.SRP
{
    // SRP is not violated here
    public class SrpFriendly
    {
        private readonly ConsoleNotifier _notifier = new ConsoleNotifier();
        private readonly ConsoleReader _reader = new ConsoleReader();
        private readonly StringValidator _validator = new StringValidator();

        public void PrintNumber(string text)
        {
            // notification sent by notifier instance
            _notifier.Notify("Enter number to the console");
            
            // input is read by reader class
            var result = _reader.Read();
            
            // input validated by the validator class
            var isNumber = _validator.Validate(result);
            
            // notification sent by notifier instance
            _notifier.Notify(isNumber
                ? $"The number entered: {result}"
                : "Input failed can not be converted to integer. Try again.");
        }
    }

    public class ConsoleNotifier
    {
        public void Notify(string text) => Console.WriteLine(text);
    }

    public class ConsoleReader
    {
        public string Read() => Console.ReadLine();
    }

    public class StringValidator
    {
        public bool Validate(string input) => int.TryParse(input, out _);
    }
}