I want to create a python function that accepts two integer parameters finds all prime numbers between them and returns these primes in a list.

I did a part of the code but I'm stuck in printing prime numbers and turning them into a list.

a,n = map(int,input("Enter a and n: ").split())
def isPrime(a,n):
   if n <= 1:
       return False
   for i in range(a, n 1):
       if n % i == 0:
           return False;

   return True

CodePudding user response：

You can make your is_prime function shorter like that:

a,n = map(int,input("Enter a and n: ").split(" "))
def is_prime(a):
    return all(a % i for i in range(2, a))

out = []
for i in range(a, n):
  if is_prime(i):
    out.append(i)
print(out)

The output for a = 0 and n = 90 would be:

[0, 1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89]

CodePudding user response：

I edited your solution so that you only check for numbers with a value of 2 or higher. Your solution allows negatives, which is not correct.

Also, your clause for checking for the primes is wrong, as you check if n has divisors. Instead, you want to check if every number in [a, n) interval has a divisor. The interval is [a, n) because a prime number has only 1 and itself as divisors.

My code does just that, so if the algorithm finds that a number in the [a, n) interval has no divisors, then it will append it in an empty list that I created before going through the loop, and return the list, then print it.

a, n = map(int, input("Enter a and n: ").split())

def isPrime(a, n):
    lst = []

    for i in range(a, n   1):
        if (i > 1):
            for j in range(2, i):
                if (i % j == 0):
                    break
            else:
                lst.append(i)

    return lst

print(isPrime(a, n))

My output for a = 0 and n = 100 is:

[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]

My code is a modified version of this.