Why can't guesses.append(guess) be above line 22?

Question

Why can't guesses.append(guess) be above line 22?
So at 4:25 Kenneth talked about not putting the 
python
guesses.append(guess)

because if the user got it right on the fifth try it would end the loop before they guessed it. I'm confused about how that is possible, the code hypothetically in  my mind seems fine above line 22 (see below). Kenneth is right the loop would end, but I don't know why
```python
it goes here
if guess == secret_num:
```

ds1 · Accepted Answer

Hi, Ryan
Good question.  I'm not nearly as knowledgeable as Kenneth, but from what I can tell by only looking at the bit of code that's viewable at 4:25, I don't see a technical problem with putting the append statement before the if statement. This is because a program doesn't exit a while loop immediately after the while loop's condition is false... it exits the while loop when the condition is re-evaluated (when it loops back up to the top).  If this wasn't the case, you'd never see the print statement outputs below when "c" has a len of > 0 when running this example:
```
def c_len():
    while len(c) == 0:
        print(len(c))
        c.append(1)
        print(len(c))
        c.append(2)
        print(len(c))
        c.append(3)
        print(len(c))
    print('the loop is already over!')
    print('last output of function')
c = []  # empty list
c_len()   # call function
```
However, maybe Kenneth is considering something else in the entire program that I can't see.  I'd be interested to hear @Chris Freeman (https://teamtreehouse.com/chrisfreeman3) 's thoughts on this... he's quite knowledgeable too!

Chris Freeman · Answer

In short, I think @Kenneth Love (https://teamtreehouse.com/kennethlove) misspoke. The append can be at line 19 or later without affecting the while loop. 
As ds1 mentioned, the while loop is only evaluated at the start of each loop. The append to guesses can not have an effect until the next loop starts. 
As Steve mentioned, perhaps Kenneth intends to keep good guesses and bad guess separated (as will be needed in a later challenge), but here there isn't an explicit reason in this code to separate them.
Kenneth is on sabbatical so it maybe sometime for him to respond to this question.

Kenneth Love · Answer

It's been awhile, but, yeah, likely just a mistake on my part. Regardless, it's good to think about when/where you're doing your mutations so that you don't get unexpected side effects.

Steven Parker · Answer

Did you actually try this in the workspace?  I don't see how it would make any difference at all (to making the list stop) if you do it before or after the test.
There would be one other difference.   If the code is before, the correct answer will go into the list, but if you put it after, the list will only contain the wrong answers.  But the loop would end either way on a correct answer because of the break

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ryan smith

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Why can't guesses.append(guess) be above line 22?

4 Answers

ds1

ds1

Chris Freeman

Chris Freeman

ds1

ds1

Steven Parker

Steven Parker

ryan smith

ryan smith

Steven Parker

Steven Parker

Kenneth Love

Kenneth Love