How to find a prime number using a function-CodePudding

def isPrime(n):
    '''
    checking n is  positive  integer or not
    '''
    val = int(n)
    if(val<1):
        return False
    return  True

The purpose of mine is to check if a number is a prime or not. So I think through checking whether the number is a positive integer or not, then will make it to be a test for prime number,

CodePudding user response：

The question is not particular clear so here is my best guess of a solution along with tests:

def is_positive(n):
      '''
      checking n is  positive  integer or not
      '''
      return isinstance(n, int) and n > 0

for i in [-1, 0, 1, '-1', '1', 1.1]:
      print(f"{i} {is_positive(i)} {type(i)}")

which prints:

-1 False <class 'int'>
0 False <class 'int'>
1 True <class 'int'>
-1 False <class 'str'>
1 False <class 'str'>
1.1 False <class 'float'>

And here is an implementation of is_prime() along with suitable tests:

def is_prime(n): 
      if not isinstance(n, int) or n <= 1:          
          return False
            
      for i in range(1, int(n/2)):   
          if not n % i:            
              return False         
      return True

for i in [-2, 0, 1, 2, 3, 4, 8.9]:
      print(f"{i} {is_prime(i)}")

which returns:

-2 False
0 False
1 False
2 True
3 True
4 False
8.9 False

CodePudding user response：

To check that something is a whole number, you can for example do (x-int(x)) == 0.

Unless you want to make sure it's an int, ie the Python type. Which is done with isinstance(int, x).

I would probably check if something is a positive integer in this way:

def isPositiveInt(num):
    if (num - int(num)) != 0:
        return False
    if num < 1:
        return False
    return True