My backwards logic
Seymore4Head
Seymore4Head at Hotmail.invalid
Fri Sep 5 19:44:47 CEST 2014
On Fri, 05 Sep 2014 10:08:18 -0700, Ethan Furman <ethan at stoneleaf.us>
wrote:
>On 09/05/2014 09:48 AM, Seymore4Head wrote:
>> I'm still doing practice problems. I haven't heard from the library
>> on any of the books I have requested.
>>
>> http://www.practicepython.org/exercise/2014/04/16/11-check-primality-functions.html
>>
>> This is not a hard problem, but it got me to thinking a little. A
>> prime number will divide by one and itself. When setting up this
>> loop, if I start at 2 instead of 1, that automatically excludes one of
>> the factors. Then, by default, Python goes "to" the chosen count and
>> not "through" the count, so just the syntax causes Python to rule out
>> the other factor (the number itself).
>>
>> So this works:
>> while True:
>> a=random.randrange(1,8)
>> print (a)
>> for x in range(2,a):
>> if a%x==0:
>> print ("Number is not prime")
>> break
>> wait = input (" "*40 + "Wait")
>>
>> But, what this instructions want printed is "This is a prime number"
>> So how to I use this code logic NOT print (not prime) and have the
>> logic print "This number is prime"
>
>Python's 'for' loop has a handy 'else' extension which is perfect for the search-type of 'for' loop:
>
> while True:
> a=random.randrange(1,8)
> print (a)
> for x in range(2,a):
> if a%x==0:
> print ("Number is not prime")
> break
> else:
> print ("Number is prime")
> wait = input (" "*40 + "Wait")
>
>Note the two lines I added after the 'break' and before the 'wait'.
I had already tried this one.
The solution I want should only print:
"This number is prime"
Adding else causes the program to also print "This number is not
prime"
I also tried the flag=True suggestion, but never got one that worked.
I am unsure when to use flag=True and flag==True
Then there is flag="True" and flag=="True"
What I really wanted was something like:
if !(a%x==0)
BTW since I am getting no grade, I much prefer the answer than a hint.
The best hint IMO is to tell me how you would do it.
Thanks everyone
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