1 ####################
   2 ## EXAMPLE: for loops over strings
   3 ####################
   4 #s = "demo loops"
   5 #for index in range(len(s)):
   6 #    if s[index] == 'i' or s[index] == 'u':
   7 #        print("There is an i or u")
   8 #
   9 #for char in s:
  10 #    if char == 'i' or char == 'u':
  11 #        print("There is an i or u")
  12 
  13 
  14 ####################
  15 ## EXAMPLE: while loops and strings
  16 ## CHALLENGE: rewrite while loop with a for loop
  17 ####################
  18 #an_letters = "aefhilmnorsxAEFHILMNORSX"
  19 #word = input("I will cheer for you! Enter a word: ")
  20 #times = int(input("Enthusiasm level (1-10): "))
  21 #
  22 #i = 0
  23 #while i < len(word):
  24 #    char = word[i]
  25 #    if char in an_letters:
  26 #        print("Give me an " + char + "! " + char)
  27 #    else:
  28 #        print("Give me a  " + char + "! " + char)
  29 #    i += 1
  30 #print("What does that spell?")
  31 #for i in range(times):
  32 #    print(word, "!!!")
  33 
  34 
  35     
  36 ####################
  37 ## EXAMPLE: perfect cube 
  38 ####################
  39 #cube = 27
  40 ##cube = 8120601
  41 #for guess in range(cube+1):
  42 #    if guess**3 == cube:
  43 #        print("Cube root of", cube, "is", guess)
  44 #        # loops keeps going even after found the cube root
  45     
  46 
  47 ####################
  48 ## EXAMPLE: guess and check cube root 
  49 ####################
  50 #cube = 27
  51 ##cube = 8120601
  52 #for guess in range(abs(cube)+1):
  53 #    # passed all potential cube roots
  54 #    if guess**3 >= abs(cube):
  55 #        # no need to keep searching
  56 #        break
  57 #if guess**3 != abs(cube):
  58 #    print(cube, 'is not a perfect cube')
  59 #else:
  60 #    if cube < 0:
  61 #        guess = -guess
  62 #    print('Cube root of ' + str(cube) + ' is ' + str(guess))
  63 
  64 
  65 ####################
  66 ## EXAMPLE: approximate cube root 
  67 ####################
  68 #cube = 27
  69 ##cube = 8120601
  70 ##cube = 10000
  71 #epsilon = 0.1
  72 #guess = 0.0
  73 #increment = 0.01
  74 #num_guesses = 0
  75 ## look for close enough answer and make sure
  76 ## didn't accidentally skip the close enough bound
  77 #while abs(guess**3 - cube) >= epsilon and guess <= cube:
  78 #    guess += increment
  79 #    num_guesses += 1
  80 #print('num_guesses =', num_guesses)
  81 #if abs(guess**3 - cube) >= epsilon:
  82 #    print('Failed on cube root of', cube, "with these parameters.")
  83 #else:
  84 #    print(guess, 'is close to the cube root of', cube)
  85 
  86 
  87 ####################
  88 ## EXAMPLE: bisection cube root (only positive cubes!)
  89 ####################
  90 #cube = 27
  91 ##cube = 8120601
  92 ## won't work with x < 1 because initial upper bound is less than ans
  93 ##cube = 0.25
  94 #epsilon = 0.01
  95 #num_guesses = 0
  96 #low = 0
  97 #high = cube
  98 #guess = (high + low)/2.0
  99 #while abs(guess**3 - cube) >= epsilon:
 100 #    if guess**3 < cube:
 101 #        # look only in upper half search space
 102 #        low = guess
 103 #    else:
 104 #        # look only in lower half search space
 105 #        high = guess
 106 #    # next guess is halfway in search space
 107 #    guess = (high + low)/2.0
 108 #    num_guesses += 1
 109 #print('num_guesses =', num_guesses)
 110 #print(guess, 'is close to the cube root of', cube)
 111