Using multiple conditions with the while loop in python

Question

I am fairly new to Python and have started making some fun little games to remember how it works. I have come across an area where I want to use more than one condition in a while loop and can't work out how to do so. I have seen on here some people doing it with numbers etc but I'm using letters and nothing I do or search for seems to work. This is what I have got so far. The idea is that the person chooses A or B (in lower or uppercase) and if they don't, that it loops back to input again.

ANS = input("\tA/B: ")
if ANS == "A":
    print("They beat you up and stole all of your stuff. You should have run away.") 
    del BAG[:]
    print("You now have", len(BAG), "items in your bag.")                             
elif ANS == "a":
    print("They beat you up and stole all of your stuff. You should have run away.") 
    del BAG[:]
    print("You now have", len(BAG), "items in your bag.")                            
elif ANS == "B":
    print("You got away but they stole something from you.")                         
    ran_item = random.choice(BAG)
    BAG.remove(ran_item)
    print("You now have", len(BAG), "items in your bag")                             
    print("They are:", BAG)
elif ANS == "b":
    print("You got away but they stole something from you.")                         
    ran_item = random.choice(BAG)
    BAG.remove(ran_item)
    print("You now have", len(BAG), "items in your bag")                             
    print("They are:", BAG)
while ANS != "A" or "a" or "B" or "b":
    print("You must make a choice...")
    ANS = input("\tA/B: ")

Wolf · Accepted Answer · 2014-02-06 21:04:01Z

3

while ANS not in ['A', 'a', 'B', 'b']:
    print...

or more generally

while ANS != 'A' and ANS != 'a' and ...

answered Feb 6, 2014 at 21:04

Wolf

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user2555451 · Accepted Answer · 2014-02-06 21:04:50Z

2

The condition of your while-loop is being interpreted by Python like this:

while (ANS != "A") or ("a") or ("B") or ("b"):

Moreover, it will always evaluate to True because non-empty strings always evaluate to True.

To fix the problem, you can use not in instead:

while ANS not in ("A", "a", "B", "b"):

not in will test if ANS can be found in the tuple ("A", "a", "B", "b").

You may also wish to use str.lower here to shorten the length of the tuple:

while ANS.lower() not in ("a", "b"):

answered Feb 6, 2014 at 21:04

user2555451

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martineau · Accepted Answer · 2014-02-06 21:09:44Z

0

The simplest way I can think of to do it in this case would be:

while ANS[0].lower() not in 'ab':
    ....

answered Feb 6, 2014 at 21:09

martineau

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