Equals not being equals

Question

Can't get python quiz program to work, when the 'useranswer' is 'correctanswer' if loop doesn't work properly and states they aren't equal even when they are. I'm wondering if this is a problem with comparing strings saved in lists, but I am really stuck for what to do to fix it. Any help would be much appreciated.

Thank you

import sys

print ("Game started")
questions = ["What does RAD stand for?",
            "Why is RAD faster than other development methods?",
            "Name one of the 3 requirements for a user friendly system",
            "What is an efficient design?",
            "What is the definition of a validation method?"]


answers = ["A - Random Applications Development, B - Recently Available Diskspace, C - Rapid Applications Development",
            "A - Prototyping is faster than creating a finished product, B - Through the use of CASE tools, C - As end user evaluates before the dev team",
            "A - Efficient design, B - Intonated design, C - Aesthetic design",
            "A - One which makes best use of available facilities, B - One which allows the user to input data accurately, C - One which the end user is comfortable with",
            "A - A rejection of data which occurs because input breaks predetermined criteria, B - A double entry of data to ensure it is accurate, C - An adaption to cope with a change external to the system"]

correctanswers = ["C", "B", "A", "A", "A"]
score = 0
lives = 4
z = 0

for i in range(len(questions)):
    if lives > 0:
        print (questions[z])
        print (answers[z])
        useranswer = (input("Please enter the correct answer's letter here: "))
        correctanswer = correctanswers[z]
        if (useranswer) is (correctanswer):     //line im guessing the problem occurs on
            print("Correct, well done!")
            score = score + 1
        else:
            print("Incorrect, sorry. The correct answer was;  " + correctanswer)
            lives = lives - 1
            print("You have, " + str(lives) + " lives remaining")
        z = z + 1
    else:
        print("End of game, no lives remaining")
        sys.exit()

print("Well done, you scored" + int(score) + "//" + int(len(questions)))

You can make the user a bit more flexible by also accepting lowercase and ignoring whitespace list this. `if useranswer.strip().upper() == correctanswer:` — John La Rooy, Feb 18 '13 at 21:50

Rohit Jain · Answer 1 · 2013-02-18T21:39:42.540

8

You should use == for comparison:

if useranswer == correctanswer:

is operator does identity comparison. And ==, >, operators do value comparison, and that is what you need.

For two objects, obj1 and obj2:

obj1 is obj2  iff id(obj1) == id(obj2)  # iff means `if and only if`.

edited Feb 18 '13 at 21:39

answered Feb 18 '13 at 21:32

Rohit Jain

209,639
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score 7 · Answer 2 · answered Feb 18 '13 at 21:32

The operators is and is not test for object identity: x is y is true if and only if x and y are the same object. Whereas the operators <, >, ==, >=, <=, and != compare the values of two objects.

Therefore...

    if (useranswer) is (correctanswer):     //line im guessing the problem occurs on

Should be...

    if useranswer == correctanswer:

Since you want to check whether the user's answer matches the correct answer. They're not the same object in memory.

Thank you, and very well explained – user2075419 Feb 18 '13 at 21:46 — user2075419, Feb 18 '13 at 21:46

score 1 · Answer 3 · edited May 23 '17 at 10:24

1

is operator tests object identity. Check the docs. I hope this SO thread might also be helpful.

edited May 23 '17 at 10:24

Community

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answered Feb 18 '13 at 21:38

Sushant Gupta

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Equals not being equals

3 Answers3