Exercise - Return Booleans from methods

Completed

Methods with Boolean return types can be simple but are useful in consolidating code. Methods that return bool values can be called to evaluate data input anywhere, in if statements, in variable declarations, and more. In this exercise, you'll gain some experience creating and using Boolean return type methods.

Create a method that returns a Boolean

Suppose you're a candidate in a coding interview. The interviewer wants you to check if several words are a palindrome. A word is a palindrome if it reads the same backwards and forwards. For example, the word racecar is a palindrome. Let's get started!

1. In the Visual Studio Code Editor, delete any existing code from the previous exercises.

2. Enter the following code into the Editor:

   string[] words = {"racecar" ,"talented", "deified", "tent", "tenet"};
   
   Console.WriteLine("Is it a palindrome?");
   foreach (string word in words) 
   {
       Console.WriteLine($"{word}: {IsPalindrome(word)}");
   }
   

   This code establishes some test cases and references a method named IsPalindrome. The words and output of the IsPalindrome method are printed in the Console.WriteLine statements.

3. Enter a new blank code line and create bool method by entering the following code:

   bool IsPalindrome(string word) 
   {
       return true;
   }
   

4. Consider how you'd check if a word is a palindrome.

   One way to check is to compare the first and the last letters of the word. If they match, then compare the second and the second-to-last letter of the word. If you reach the middle of the word, then all the letters have been compared and matched. If any letters don't match, the word isn't a palindrome.

5. Update the IsPalindrome method with the following code:

   bool IsPalindrome(string word) 
   {
       int start = 0;
       int end = word.Length - 1;
   
       while (start < end) 
       {
           if (word[start] != word[end]) 
           {
               return false;
           }
           start++;
           end--;
       }
   
       return true;
   }
   

   Notice the variables start and end to point to the first and last characters in the string. The loop breaks when the middle of the word is met; when start and end point to the same character or cross over each other. The pointers are moved inwards each time there's a match. If they don't match, the method terminates and returns false.

   Now your method successfully checks if a word is a palindrome and returns true or false accordingly.

Check your work

In this task, you'll run your application from the Integrated Terminal and verify your code is working correctly. Let's get started.

1. Save your work using Ctrl + S or using the Visual Studio Code File menu.

2. If necessary, open Visual Studio Code's Integrated Terminal panel.

   In the EXPLORER panel, to open a Terminal at your TestProject folder location, right-click TestProject, and then select Open in Integrated Terminal.

3. At the Terminal command prompt, enter dotnet run

4. Verify that your code produces the following output:

   Is it a palindrome?
   racecar: True
   talented: False
   deified: True
   tent: False
   tenet: True
   

   If your code displays different results, you'll need to review your code to find your error and make updates. Run the code again to see if you've fixed the problem. Continue updating and running your code until your code produces the expected results.