CODEWITHSUNDEEP
pythonpython-3.x
Baitalon
Baitalon

Reputation: 321

How to check if number is prime if no divisibles

I'm new to programming, I need to know if it's possible to print a string like "This is a prime number" if there were no results for i

n = int(input("Digite um número inteiro positivo: "))
for i in range(2,n):
    if n % i == 0:
         print(i)

For example if I typed 5 Nothing show up

If I typed 8 it would show 2 and 4

How can I add a print(n,"is a prime number") if NOTHING shows up in the program? I couldn't find any command for that

Upvotes: 0

Views: 106

Answers (4)

beJeb
beJeb

Reputation: 7

You could also set the range of the loop to only check values from 2 to n//2 because anything past that would be unnecessary for checking if prime. 

def isPrime(n):
    for i in range(2,**n//2**):
        if n % i == 0:
            return 'This number is not Prime.'
    else:
        return 'This number is Prime.'


def main():
    user = int(input('Enter a number to check primeness: '))
    print(isPrime(user))

main()

Upvotes: 0

Pete
Pete

Reputation: 489

def isPrime(num):
    for i in range(2, num):
        if num % i == 0:
            return False
    return True

def getFactors(n):
    myList = []
    for i in range(2, n):
        if n % i == 0:
            myList.append(i)
    return myList

num = 17
num2 = 20
if isPrime(num):
    print("prime")
else:
    print(getFactors(17))
if isPrime(num2):
    print("prime")
else:
    print(getFactors(num2))

Upvotes: 0

Priyom
Priyom

Reputation: 1

A crude way to do it would be adding something like a counter which checks the number of factors.

n=int(input("Digite um número inteiro positivo:"))
counter=0
for i in range(2,n):
    if(n%i==0):
        print(i)
        counter+=1
if(counter==0):
    print "n is prime"

Upvotes: 0

Rory Daulton
Rory Daulton

Reputation: 22544

n = int(input("Digite um número inteiro positivo: "))
printed = False
for i in range(2,n):
    if n % i == 0:
         print(i)
         printed = True
if not printed:
      print(n,"is a prime number")

This uses a "flag" variable to show if a value was printed.

Upvotes: 2

Related Questions