Some help in function exercise (python)

Question

The exercise speaks the following :

"Write a function that takes a positive integer m and returns 1 if m is prime, 0 otherwise."

My attempt :

Edit: Then , performed the modifications the program is still not returning the values of 1 or 0 ( if the number is odd or even).

m = int(input("Digite um numero inteiro:"))    

def recebe_m(m):

  n_divisores = 0
  i = 1

  while(i <= m):        
      if(m%i==0):           
          n_divisores = n_divisores + 1

  i = i+1

  if(n_divisores==2):
      return(1)
 else:
      return(0)

  print(recebe_m(m))

BS : I have chosen to leave the i <= m , I hope you have no problem.

I’m getting the following python error :

Unboundlocalerror: local variable 'i' referenced before assignment

Answer 1

You need to declare the variable i within the function recebe_m. The same problem will occur with the variable n_divisores, declare the same within the function.

m = int(input("Digite um numero inteiro:"))    
def recebe_m(m):
     n_divisores = 0
     i = 1
     while(i <= m/2):        
        if(m%i==0):           
           n_divisores = n_divisores + 1

        i = i+1

    if(n_divisores==1):
        return(1)
    else:
        return(0)
print(recebe_m(m))

Also, as the friend of the other answer said, you are trying to divide by 0 in the first iteration of your while loop, fix it and boot i with 1.

The problem with your code is variable scope. In python if you declare a variable in a more internal scope, and the same variable exists in a global scope, the variable of the most internal scope will be the one used by python to make the calculations.

In your code you try to declare and increment a variable on the same line in a case that the variable i does not exist in the internal scope yet, which causes the error. The same goes for n_divisores.

To better understand:

x = 10
def func():
    x = 5
    print(x)
func() # printa 5
print(x) # printa 10, x com valor 5 morreu.

Edit: As @Anderson said, it’s not necessary to check all the numbers, but only half of them (i <=m/2)

Answer 2

I tried to make the function as simple as possible

You do not need to account for the divisors, if there is any divisor between 1 and half of itself, you can already define that the number is not prime.

The following function runs through all numbers of 2 até m/2, and if you find any splitter returns 0, if it finishes the loop without finding any it returns 1

m = int(input("Digite um numero inteiro:"))

def recebe_m(m):
  for i in range(2, int(m/2)):
    if m%i==0:           
      return(0)

  return(1)

print(recebe_m(m))

Answer 3

From what I could see, would you have the intention a [int]%0 in the first case? It is not divided by zero haha (a n to be q want to open a black hole rsrs)

You need to declare the variable n_divisors within def

the code stays:

m = int(input("Numero: "))
def recebe_m(m):
    cont=0
    for x in range(1,m+1):        
        if(m%x==0):
            cont+=1    
    if(cont==2):
        return(1)
    else:
        return (0)

print(recebe_m(m))