Prime number calculator used as part of a debugging tutorial on talktotheduck.dev

prime_main.py

import math
import time
import six

if six.PY2:
    # In python2, range returns a list instead of an iterator. When running on a large range,
    # this can take up all of the available memory and crash the process.
    range = xrange


def isPrime(num):
    if num == 2:
        return True
    if num < 2 or num % 2 == 0:
        return False
    sqrt_num = int(math.sqrt(num))
    for i in range(3, sqrt_num + 1, 2):
        if num % i == 0:
            return False
    return True


def main():
    print("Calculating number of primes")
    cnt = 0
    start = time.time()
    for i in range(2, 10 ** 9):
        if isPrime(i):
            cnt += 1
    print("Total number of primes: ", cnt)
    print("Took ", time.time() - start, " seconds")


if __name__ == '__main__':
    main()