My code works in python IDLE and works for the Example, but I can't pass the challenge!

Question

Here's the code I tested in my IDLE, it works!

test.py

def members(dictionary, li):
    idx = 0
    count = 0
    while idx < len(dictionary):
        if li[idx] in dictionary:
            count += 1
        idx += 1
    return count

#test
my_dict = {'apples': 1, 'bananas': 2, 'coconuts': 3}
my_list = ['apples', 'coconuts', 'grapes', 'strawberries']

print(members(my_dict, my_list))

But I can't pass the challenge! Any idea ?

counts.py

# You can check for dictionary membership using the
# "key in dict" syntax from lists.

### Example
# my_dict = {'apples': 1, 'bananas': 2, 'coconuts': 3}
# my_list = ['apples', 'coconuts', 'grapes', 'strawberries']
# members(my_dict, my_list) => 2

def members(dictionary, li):
    idx = 0
    count = 0
    while idx < len(dictionary):
        if li[idx] in dictionary:
            count += 1
        idx += 1
    return count

Answer 1 · 2016-09-29T04:37:32Z

September 29, 2016 4:37am

Extremely close to the right answer!

I ran your code locally - and it gave me the right answer! But when I changed the parameters it gave me the wrong answer.

Here is how I found the issue:

my_dict = {'apples': 1, 'bananas': 2, 'coconuts': 3}
my_list = ['apples', 'coconuts', 'grapes', 'strawberries', 'bananas']

I added 'bananas' to my_list and ran this locally - it returned 2, instead of the expected 3.

The problem is that you chose to loop until your counter had reached the length of the dictionary - and that works unless the list is longer than the dictionary. Here is the very slight change to your code, see if you can figure out why this works where your code didn't:

def members(dictionary, li):
    idx = 0
    count = 0
    while idx < len(li):
        if li[idx] in dictionary:
            count += 1
        idx += 1
    return count

Please comment and let me know if you have any questions, I'm happy to explain further.

Welcome to the Treehouse Community

Looking to learn something new?

oliverchou

oliverchou

My code works in python IDLE and works for the Example, but I can't pass the challenge!

1 Answer

Jacob Herrington

Jacob Herrington

oliverchou

oliverchou