// Zorah Fung, CSE 142
// Examples of methods that return booleans
public class BooleanMethods {
   public static void main(String[] args) {
      System.out.println("banana: " + hasVowel("banana"));
      System.out.println("crwth: " + hasVowel("crwth"));    
   }
   
   // Returns true if the given word contains a vowel, false otherwise
   public static boolean hasVowel(String word) {
      word = word.toLowerCase();
      for (int i = 0; i < word.length(); i++) {
         char c = word.charAt(i);
         char c2 = word.substring(i, i + 1).charAt(0);
         if (isVowel(c)) {
            return true;
         }
      }
      return false;
   }
   
   // Returns true if the given lowercase letter is a vowel, false otherwise
   public static boolean isVowel(char c) {
      boolean vowel = c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
      return vowel;
   }
   
   // Returns true if the given lowercase letter is not a vowel (consonant), false otherwise
   public static boolean isNonVowel(char c) {
      // Equivalent to !isVowel(c)
      // In order to negate the expression from isVowel, we both negate the tests
      // in each expression, as well as flip the logical operator from || to && using
      // DeMorgan's Law
      return c != 'a' &&  c != 'e' && c != 'i' && c != 'o' && c != 'u';
   }
}