On Jul 15, 7:28 pm, Mensanator <[EMAIL PROTECTED]> wrote: > On Jul 15, 11:26 am, defn noob <[EMAIL PROTECTED]> wrote: > > > > > isPrime works when just calling a nbr but not when iterating on a > > list, why? adding x=1 makes it work though but why do I have to add > > it? > > Is there a cleaner way to do it? > > > def isPrime(nbr): > > for x in range(2, nbr + 1): > > if nbr % x == 0: > > break > > if x == nbr: > > return True > > else: > > return False > > > >>> [isPrime(y) for y in range(11)] > > > Traceback (most recent call last): > > File "<pyshell#45>", line 1, in <module> > > [isPrime(y) for y in range(11)] > > File "C:\Python25\Progs\blandat\myMath.py", line 9, in isPrime > > if x == nbr: > > UnboundLocalError: local variable 'x' referenced before assignment > > > >>> map(isPrime, range(100)) > > > Traceback (most recent call last): > > File "<pyshell#38>", line 1, in <module> > > map(isPrime, range(100)) > > File "C:\Python25\Progs\blandat\myMath.py", line 9, in isPrime > > if x == nbr: > > UnboundLocalError: local variable 'x' referenced before assignment>>> > > isPrime(10) > > False > > >>> isPrime(11) > > > True > > > adding x=1 makes it work though: > > > def isPrime(nbr): > > x=1 > > for x in range(2, nbr + 1): > > if nbr % x == 0: > > break > > if x == nbr: > > return True > > else: > > return False > > > >>> [isPrime(y) for y in range(11)] > > > [False, True, True, True, False, True, False, True, False, False, > > False] > > No, it doesn't. You are falsely reporting that 1 is prime. > > And instead of making the fake variable x, shouldn't you > instead test that nbr+1 is greater than 2? Or call it with > range(3,11) instead of range(11)? x isn't initialized > because if nbr+1 is <=2, the for loop has an invalid range > and doesn't even execute.
def isPrime(nbr): for x in range(2, nbr + 1): if nbr % x == 0: break if x == nbr: return True else: return False this works for all primes, if i want to not include 1 i just do if nbr<=1 return false you are answering the wrong question. anyway here is a clear one: def isPrime(nbr): if nbr < 2: return False for x in range(2, nbr + 1): if nbr % x == 0: return nbr == x -- http://mail.python.org/mailman/listinfo/python-list