What is wrong with this isPrime function?-CodePudding

I'm making an isPrime function. Any odd number that I put in (unless it's 1, 2 or 3, which break it) says that it is prime even when they clearly aren't.

from even import *

num = input("What number? ")


def isPrime(n):
   n = int(n)
   if isEven(n):
      return False

   i = 2
   while i < n:
      a = n / i
      if isinstance(a, int):
          return False

      else:
          d = n - 2
          if i == d:
              return True

          else:
              i  = 1


if isPrime(num) is True:
   print(num   " is a prime number!")

if isPrime(num) is False:
   print(num   " is not a prime number!")

And the code for the isEven function is here:

def isEven(num):
    if num == 0:
        return True

    elif num % 2 == 0:
        return True

    else:
        return False

What am I doing wrong? Also, any general tips for improving my code?

CodePudding user response：

Here is what you meant to type. This is not the best way, but this is parallel to the approach you were taking:

def isEven(num):
    return num % 2 == 0

def isPrime(n):
    if isEven(n):
        return False

    for i in range(2,n//2):
        if n % i != 0:
            return False
    return True

num = int(input("What number? "))

if isPrime(num):
    print(num, "is a prime number!")
else:
    print(num, "is not a prime number!")