[Tutor] Generate Prime Numbers

[Alan Gauld]

On 29/05/15 16:28, Mirage Web Studio wrote:

> Below is a sample code i created.
>
> Can i better it any way?

Of course. There is always improvements that can be made.
But in your case there are quite a few!

> def IsDivisibleBy3(number):#string variable
>      v=0
>      for c in number:
>          v=v+int(c)
>      if v%3==0:
>          return True
>      else:
>          return False

def IsDivisibleBy3(number):#string variable
     return not int(number) % 3

> def IsDivisibleBy7(number):#string variable

See above, but maybe better still

def isDivisibleByN(number, N):
    return not int(number)%N

> def IsPrime(number):

Google for the "sieve of eratosthenes"
Or look it up on wikipedia.

That will give one of several possible
improvements to your algorithm.

> primelist=[]
>
> for i in range (11,200000,2):
>      number=str(i)
>      print "checking ",i
>
>      if IsPrime(number):

Note, you are starting with a number, then converting
it to a string then in your functions converting it
back to a number.
That's crazy!

Also where do you store the primes less than 11?
ie. 1,3,5,7

HTH
-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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