C# programming exercises - examples with solutions

String in reverse order (recursion)

Given a string, write a method that prints it in reverse order.

Expected input and output

StringInReverseOrderRecursion("abcde") → "edcba" StringInReverseOrderRecursion("Sed lectus est, elementum ut urna eu") → "ue anru tu mutnemele ,tse sutcel deS"

Click here to see example solution

using System;

namespace CSharpExercises.Exercises.Recursion
{
    class StringInReverseOrderRecursionTask
    {
        static string StringInReverseOrderRecursion(string str)
        {
            return str.Length > 0 ? str[str.Length - 1] + StringInReverseOrderRecursion(str.Substring(0, str.Length - 1)) : str;
        }

        static void Main(string[] args)
        {
            var str1 = "A";
            var str2 = "34 ( 9  9@*";
            var str3 = "eMpIrE";
            var str4 = string.Empty;

            Console.WriteLine(StringInReverseOrderRecursion(str1)); // A
            Console.WriteLine(StringInReverseOrderRecursion(str2)); // *@9  9 ( 43
            Console.WriteLine(StringInReverseOrderRecursion(str3)); // ErIpMe
            Console.WriteLine(StringInReverseOrderRecursion(str4)); //
        }
    }
}