not all code paths return a value

First of all, forgive my lack of knowledge, I am fairly new to programming but I have a high level of interest in the subject. We were working on a bit of code in class yesterday and we even stumped our teacher, who then took most of the class trying variations of this code. We were attempting to write a program that would determine if input was a palindrome. The only way I could think to do it was as follows, but I kept getting the error message in the title:

Code:

 class Program
   {
      public static bool isPalindrome(int first, string word, int last)
      {
         if (word[first] != word[last])
         {
            return false;
         }
        
         else if (first < last)
         {
            isPalindrome(first + 1, word, last - 1);
         }

         else
            return true;        
      }

      static void Main(string[] args)
      {
         string word;
         Console.WriteLine("Enter a word to test: ");
         word = Console.ReadLine();

         int last = word.Length - 1;

         bool palindromeTest = isPalindrome(0, word, last);

         if (palindromeTest == true)
         {
            Console.WriteLine("Yes the word is a palindrome.");
         }
         else
            Console.WriteLine("No, that word is not a palindrome");


      }
   }

I guess my question is- in what scenario would a call of the method not return a value? Thanks for any help.

 

Your main function is not returning any value and so you are getting that error.

Code:

         if (palindromeTest == true)
         {
            Console.WriteLine("Yes the word is a palindrome.");
         }
         else
            Console.WriteLine("No, that word is not a palindrome");

Just make sure you have a return statement after the if else or inside each of if else.