Myujth

I'm writing a short snippet for a class that is supposed to run through a given list of numbers and append any primes. Right now it is returning all numbers in the range though.

I've found examples online for how to do this, but wanted to try it myself but I've seem to hit a wall... Here is my code:

from random import randrange
from time import sleep

def prime():
 user_num = eval(input("Input a number: "))
 list_prime = 
 for i in range(2,user_num):
 if (i % 2) == 1 and
 (i % 3) == 1 and
 (i % 4) == 1 and
 (i % 5) == 1 and
 (i % 6) == 1 and
 (i % 7) == 1 and
 (i % 8) == 1 and
 (i % 9) == 1 or
 i == 2:
 list_prime.append(i)

if list_prime == '':
 print('No prime numbers.')
if list_prime != '':
 print('nPrime numbers from 1 to ' + str(user_num) + ': ' + str(list_prime))

sleep(1)
print('nClosing console in 60 seconds...')
sleep(60)

prime()

As he said, you werent correctly checking for prime numbers.

from random import randrange
from time import sleep

list_prime = 
user_num = 0

def prime():
 user_num = eval(input("Input a number: "))
 for i in range(2,user_num):
 j = 2
 isprime = 1
 while (j <= i/2):
 if (i % j == 0):
 isprime = 0
 break
 j+=1
 if (isprime == 1):
 list_prime.append(i)

prime()
if list_prime == '':
 print('No prime numbers.')
if list_prime != '':
 print('nPrime numbers from 1 to ' + str(user_num) + ': ' + str(list_prime))

sleep(1)
print('nClosing console in 60 seconds...')
sleep(60)

Checking if the result of a modulo operation is 1 is not the correct approach. For example, 6 % 5 is 1, but 6 definitely isn't a prime number. Instead, for each suspect N you should check that no number X exists such that N % X == 0.

A wildly sub-optimal implementation could look like this:

list_prime = 
for i in range(2, user_num):
 if all(n % x for x in list_prime):
 list_prime.append(i)