CODEWITHSUNDEEP
pythonwhile-loopraw-input
sfowler12
sfowler12

Reputation: 35

Python: Repeating a function when raw_input is not valid

I'm want to be able to determine if an input is valid. I have:

servqual = raw_input(">").lower()
while servqual != "great" or "good" or "lacking" or "poor":
    print "I didn't understand that. Please try again."
    servqual = raw_input(">").lower()

However, whenever I run it through the loop it always assumes True, even if I input a valid answer. I've looked over different answers but none of them seem to work in this scenario.

Upvotes: 0

Views: 438

Answers (2)

nisargjhaveri
nisargjhaveri

Reputation: 1509

servqual != "great" or "good" or "lacking" or "poor"

is equivalent to 

(servqual != "great") or "good" or "lacking" or "poor"

And since Strings are considered True, you are always getting it True

The correct way to do it is

servqual != "great" and servqual != "good" and servqual != "lacking" and servqual != "poor"

or 

servqual not in ("great", "good", "lacking", "poor")

Your final code will look like

servqual = raw_input(">").lower()
while servqual not in ("great", "good", "lacking", "poor"):
    print "I didn't understand that. Please try again."
    servqual = raw_input(">").lower()

You can further improve it by using following construct.

while raw_input(">").lower() not in ("great", "good", "lacking", "poor"):
    print "I didn't understand that. Please try again."

Upvotes: 5

khelwood
khelwood

Reputation: 59222

You have:

while servqual != "great" or "good" or "lacking" or "poor":

This means the same as:

while (servqual != "great") or "good" or "lacking" or "poor"

Since "good" or "lacking" or "poor" is always true, the whole condition is true.

Rather than that, you can do this:

while servqual not in ("great", "good", "lacking", "poor"):
    ...

Upvotes: 1

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