9. Bugz¶

Walkthrough¶

This is LaunchScrabble, a unique version of Scrabble! This function takes a list of words from a LaunchScrabble game and calculates the player’s score. All words count as one point, but words that begin with ‘q’ are 10 points!

But since ‘q’ words are worth so many points, we want to make sure our players aren’t cheating and making up words that start with ‘q’. So for every word that begins with ‘q’, the program checks to make sure the following letter is ‘u’. If we find an exception, for instance “qrie”, negate all their points and give that cheater an overall score of 0!

The only problem is, the code we have so far doesn’t work.

def launch_scrabble(words): points = 0 for word in words: points += 1 # equivalent to points = points + 1 if (word[0] == "q" and word[1] == "u"): points += 10 else: return 0 return points test_words_1 = ['dog'] print('test_words_1 score:', launch_scrabble(test_words_1)) test_words_2 = ['quiet'] print('test_words_2 score:', launch_scrabble(test_words_2))

Problems:

1. All words that do not begin with ‘q’ will automatically return 0
2. q words add 11 to the total points

There are a couple ways to fix this (for instance, you could use nested conditionals or boolean logic to deal with the ‘q’ words), but one possible solution is below.

def launch_scrabble(words): points = 0 for word in words: if (word[0] == "q"): if (word[1] == "u"): points += 10 else: return 0 else: points += 1 return points test_words_1 = ['dog'] print('test_words_1 score:', launch_scrabble(test_words_1)) test_words_2 = ['quiet'] print('test_words_2 score:', launch_scrabble(test_words_2))

Studio¶

Today’s studio, rather than explicitly pertaining to strings, is more of an overall review. You will get some practice debugging a variety of common mistakes that new coders make.

Below are a handful of code snippets that are broken. See if you can fix them!

Printing the ith Element

The function below, print_every(i, nums) receives a list of numbers nums, along with an integer i. The function is supposed to print every ith element from the list. But it’s not working!

# in a list of numbers, print every ith number def print_every(i, nums): counter = 0 for i in nums: if counter % i == 0: print(i) counter += 1 print_every(3, [4, 7, 2, 10, 1, 0, 9, 6]) # should print 4, then print 10, then print 9

Seniors Bar

You are the bouncer outside the door of a seniors only bar. People must be 70 or older, otherwise they are not allowed in. When a group of friends arrives, your job is to determine whether to accept or reject the group. The function below, check_group, is supposed to return a boolean indicating whether or not the group is allowed inside. But it’s not working!

# return True if every member of the group is at least 70, otherwise return False def check_group(ages): for age in ages: if age < 70: return False else: return True from test import testEqual # this group should not be allowed inside the bar group = [78, 71, 25, 84] testEqual(check_group(group), False) # this group should also not be allowed inside the bar group2 = [ 2, 99 ] testEqual(check_group(group2), False) # this loner is allowed group3 = [ 99 ] testEqual(check_group(group3), True)

Password Check

When registering for an online account, users must create a password. For your service, you enforce the following rules on passwords: The password must contain at least one non-alphabetical character, and may not contain any spaces. The function below is supposed to check the validity of passwords. But! It’s! Not! Working!

def password_checker(password): """ A valid password has no spaces, and at least one non-alphabetical character """ contains_non_alpha = False for char in password: if char == " ": return False else not char.isalpha(): contains_non_alpha = True return contains_non_alpha pw1 = "i <3 makonnen" print(password_checker(pw1)) # should print False pw2 = "puzzlesareforfun" print(password_checker(pw2)) # should print False pw2 = "puzzlesr4fun" print(password_checker(pw2)) # should print True