Python Input Function

Question

I was wondering if somebody could tell me what is wrong with this code, when I run the code it shows nothing but if I take out the "elif" it does work.\

first=input("What is your first name? ");
middle=input("What is your middle name? ");
last=input("What is your last name? ");
test = [first, middle, last];
print ("");
print ("Firstname: " + test[0]);
print ("Middlename: " + test[1]);
print ("Lastname: " + test[2]);
print ("");
correct=input("This is the information you input, correct? ");
if (correct == "Yes" or "yes"):
 print ("Good!")
elif (correct == "no" or "No"):
 print ("Sorry about that there must be some error!");

• John La Rooy: People have pointed out that the tests in your if and else are probably not what you want, but are you sure it really prints nothing??
• msw: To amplify @gnibbler, False or "yes" → True and True or "yes" → True therefore print("Good!") should always execute regardless of the value of correct.

Answer 1

Here's the problem:

if (correct == "Yes" or "yes"):
 # ...
elif (correct == "no" or "No"):
 # ...

It should be:

if correct in ("Yes", "yes"):
 # ...
elif correct in ("No", "no"):
 # ...

Notice that the right way to make a comparison involving several conditions is like this:

correct == "Yes" or correct == "yes"

But usually it gets written like this, which is shorter:

correct in ("Yes", "yes")

• user2812028: I input that and it still doesn't have an output of anything.

Answer 2

You need to use the in keyword:

if correct in ("Yes", "yes"):
 print ("Good!")
elif correct in ("no", "No"):
 print ("Sorry about that there must be some error!")

or convert the entire input to the same case:

# I use the lower method of a string here to make the input all lowercase
correct=input("This is the information you input, correct? ").lower()
if correct == "yes":
 print ("Good!")
elif correct == "no":
 print ("Sorry about that there must be some error!")

Personally, I think the lower solution is the cleanest and best. Note however that it will make your script accept inputs such as "YeS", "yEs", etc. If this is a problem, go with the first solution.

Answer 3

You'e checking correct incorrectly

if (correct == "Yes" or "yes"):

means (correct == "Yes") or ("yes"), and non-empty string evaluates to True in python, so first condition will always be True.If you want to check multiple strings, you can do:

if (correct in ("Yes", "yes")):

But this one doesn't takes 'yEs' or 'yES' into account. If you want case-insensitive comparison, then I think correct.lower() == "yes" would be preferred method.