using System;

namespace StringMetotlari
{
    internal class Program
    {
        static void Main(string[] args)
        {
            string ad = "Altan Emre Demirci";

            Console.WriteLine("Uzunluk: " + ad.Length);
            Console.WriteLine("E index: " + ad.IndexOf("E"));
            Console.WriteLine("Buyuk: " + ad.ToUpper());
            Console.WriteLine("Replace: " + ad.Replace("e", "a"));
            Console.WriteLine("Substring: " + ad.Substring(0, 5));

            string iban = "TR123456789012";
            if (iban.StartsWith("TR") && iban.Substring(2).Length == 12)
            {
                Console.WriteLine("IBAN dogru girildi");
            }
            else
            {
                Console.WriteLine("IBAN hatali");
            }
        }
    }
}