Python program to find the factorial of a number using recursion

Question

A factorial of a number is the product of all the integers from 1 to that number.

For example, the factorial of 5 (denoted as 5!) is 1*2*3*4*5 = 120. The factorial of 0 is 1.

def recur_factorial(x):

    if x == 1:
        return 1
    else:
        return (x * recur_factorial(x - 1))

num = int(input("Enter number: "))

print("The factorial of", num, "is", recur_factorial(num))

So I would like to know whether I could make this program shorter and more efficient.

Also, I would like to know the advantages and disadvantages of recursion.

Answer 1

Looking over your code, this is what I have for you:

• Your function can be turned into a one-liner
• You should use if __name__ == '__main__' to ensure you're not running this program externally.

Refactored Code:

def recur_factorial(x):
  return 1 if x == 1 else (x * recur_factorial(x - 1))

def main():
  num = int(input("Enter number: "))
  print("The factorial of", num, "is", recur_factorial(num))

if __name__ == '__main__':
  main()

You can read this StackOverflow question for more information about the advantages and disadvantages of recursion