[Tutor] comparison on Types

[Ian D]

Ok thanks. I thought it would be better with just a while True loop; for simple clarity.

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> Date: Wed, 29 Apr 2015 21:14:06 +1000
> From: steve at pearwood.info
> To: tutor at python.org
> Subject: Re: [Tutor] comparison on Types
>
> On Wed, Apr 29, 2015 at 09:44:28AM +0000, Ian D wrote:
>
>> I was looking at the example code below. I am using python 2.7.
>>
>> I am wondering why when I substitute the while n! = "guess" to while
>> n!= guess (<-- no quotes) I get a problem?
>
> Really? What sort of problem? It looks okay to me, although I haven't
> run it.
>
>
>> The Type string is used for the first conditional comparison in the
>> outer While loop, but afterwards the Type is an int.
>>
>> I would have expected the guess variable to be used as Type int as it
>> seems to be cast in the raw_input statement and would be comparable to
>> another int that's stored in variable n. Thanks
>
> I'm having difficulty understanding your question. It might help if you
> explain what you think the code should do, versus what it actually does.
> Do you get an error? Then post the full error traceback, starting from
> the line "Traceback" to the end.
>
> It also might help to understand that in Python, *variables* don't have
> types, but values do. Variables can take any value, and take on the type
> of that value until such time as they change to a different value:
>
> py> x = "Hello"
> py> type(x)
> <type 'str'>
> py> x = 23
> py> type(x)
> <type 'int'>
>
>
>
>
> Looking at your code, I can see only one obvious (to me) problem:
>
>> import random
>> n = random.randint(1, 99)
>> guess = int(raw_input("Enter an integer from 1 to 99: "))
>> while n != "guess":
>
> By using the string "guess", you guarantee that n is *never* equal on
> the first test. That means that the loop will be entered. If you remove
> the quotation marks, and compare n != guess (here guess is the variable,
> not the literal string) then if your guess happens to be correct on the
> first time, the while loop will not be entered and the program will just
> end.
>
> print
>> if guess < n:
>> print "guess is low"
>> guess = int(raw_input("Enter an integer from 1 to 99: "))
>> elif guess> n:
>> print "guess is high"
>> guess = int(raw_input("Enter an integer from 1 to 99: "))
>> else:
>> print "you guessed it!"
>> break
>> print
>
>
> Try this instead:
>
>
> import random
> n = random.randint(1, 99)
> guess = 0 # Guaranteed to not equal n.
> while n != guess:
> guess = int(raw_input("Enter an integer from 1 to 99: "))
> print
> if guess < n:
> print "guess is too low"
> elif guess> n:
> print "guess is too high"
> else:
> print "guessed correctly!"
>
>
>
>
> Does that help?
>
>
>
> --
> Steve
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