// Helene Martin, CSE 142
// Several methods that I think have interesting characteristics.

import java.util.*;

public class Practice {
   public static void main(String[] args) {
      System.out.println(isAllVowels("aeiouAEIOU")); // true
      System.out.println(isAllVowels("ooooOOOooOOOh")); // false
      
      System.out.println();
      System.out.println(hasNoVowels("tqqqaqr")); // false
      System.out.println(hasNoVowels("qwrrrtpppp")); // true
      
      System.out.println();
      System.out.println(digitSum(29107)); // 19
      System.out.println(digitSum(-23)); // 5
      
      System.out.println();
      System.out.println(hasAnOddDigit(34442)); // true
      System.out.println(hasAnOddDigit(222)); // false
      
      System.out.println();
      System.out.println(stutter("hello"));
      System.out.println(stutter("CSE 142"));
   }
   
   // isAllVowels returns true if all characters are vowels
   // aaaaaahiuuuuuuu (first, we solved the problem by hand
   public static boolean isAllVowels(String str) {
      for (int i = 0; i < str.length(); i++) {
         char c = str.charAt(i);
         
         if (isNonVowel(c + "")) {
            return false;
         }
      }
      return true;
   }
   
   // returns true if phrase has no vowels, false otherwise
   // NOTE: we can't use isAllVowels!
   public static boolean hasNoVowels(String phrase) {
      for (int i = 0; i < phrase.length(); i++) {
         String s = phrase.substring(i, i + 1);
         // String s = phrase.charAt(i) + ""
         if (isVowel(s)) {
            return false;
         }
      }
      return true;
   }
   
   // digitSum accepts an integer parameter and returns the sum of its digits
   public static int digitSum(int value) {
      // 4523 % 10 -> 3
      // 4523 / 10 -> 452
      // 452 % 10 --> 2
      value = Math.abs(value); // for negatives
      
      int sum = 0;
      
      while (value > 0) {
         int digit = value % 10;
         value = value / 10;
         
         sum += digit;
      }
      return sum;
   }
   
   // Write a method called hasOddDigit that takes an integer as a
   // parameter and that returns true if it has an odd digit, false if
   // it does not.  You may assume that n is greater than or equal to 0.
   public static boolean hasOddDigit(int n) {
      while (n > 0) {
         int digit = n % 10;
         if (digit % 2 != 0) {
            return true;
         }
         n = n / 10;
      }
      return false;
   }
   
   // Write a method called stutter that takes a string as a parameter
   // and that returns a new string where each letter of the original
   // string has been replaced with two of that letter.  For example,
   // stutter("hello") should return "hheelllloo"
   public static String stutter(String s) {
      String response = ""; // cummulative sum pattern
      for (int i = 0; i < s.length(); i++) {
         char ch = s.charAt(i);
         response = response + ch + ch;
      }
      return response;
   }
   
   // isVowel returns whether a String is a vowel (a, e, i, o, or u),
   // case-insensitively.
   public static boolean isVowel(String s) {
      s = s.toLowerCase(); // or use equalsIgnoreCase
      return s.equals("a") || s.equals("e") || s.equals("i")
      || s.equals("o") || s.equals("u");
   }
   
   // isNonVowel returns whether a String is any character except a vowel.
   public static boolean isNonVowel(String s) {
      //s = s.toLowerCase();
      //return !s.equals("a") && !s.equals("e" ... De Morgan's law
      return !isVowel(s);
   }
}