Python factorial program output

Question

Am trying to write one factorial program in python, in which if I am giving input values as starting value of 1 and count 5 , it should give 1,2,6,24,120 .. but am facing logic error while executing could some help me where am doing the mistake

def getting_input():
while True:
    try:
        x=int(input("Enter the value:"))
        return x
    except Exception as e:
        print(f"error :{e}")
        continue

class factorial:
def __init__(self):
    self.x = getting_input()
    self.y = getting_input()
def fact(self):
    for i in range(self.x,self.y):
        c=list()
        self.result=1
    while i==0 or i==1:
        return 1
    else:
        return i * fact(i-1)
        self.result=fact(self)
        c.append(self.result)
    d={'factorial': c}
    print(d)
obj=factorial()
obj.fact()

Output:

Enter the value:1
Enter the value:5
Traceback (most recent call last):
 File "C:/Users/Desktop/TOM/f.py", line 27, in <module>
 obj.fact()
File "C:/Users/Desktop/TOM/f.py", line 21, in fact
return i * fact(i-1)
NameError: name 'fact' is not defined

Attachments area

Please indent your code well as like you tried it. To call fact method inside the class you may do self.fact() — azro
– azro, Commented Sep 6, 2020 at 12:37
Does this answer your question? Why is instance variable not getting recognized — Tomerikoo
– Tomerikoo, Commented Sep 6, 2020 at 12:41

Aviv Yaniv · Accepted Answer · 2020-09-06 12:48:19Z

0

You get NameError: name 'fact' is not defined as you should use self. before calling to a method of the class.

This is a mitigation for the code:

Calculate factorial for x with recursion
Calculate factorial from x to y iteratively

def getting_input():
    while True:
        try:
            x=int(input("Enter the value:"))
            return x
        except Exception as e:
            print(f"error :{e}")
            continue

class factorial:
    def __init__(self):
        self.x = getting_input()
        self.y = getting_input()
    def rec_factorial_calculation(self, i):
        if i==0 or i==1:
            return 1
        else:
            return i * self.rec_factorial_calculation(i-1)
    def fact(self):
        last_factorial = self.rec_factorial_calculation(self.x)
        c = [last_factorial]
        for i in range(self.x+1, self.y + 1):
            last_factorial *= i
            c.append(last_factorial)
        d = {'factorial': c}
        print(d)

obj=factorial()
obj.fact()

Output:

Enter the value:1
Enter the value:5
{'factorial': [1, 2, 6, 24, 120]}

edited Sep 6, 2020 at 12:48

answered Sep 6, 2020 at 12:41

Aviv Yaniv

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1 Comment

Aviv Yaniv Over a year ago

Welcome @SivaguruNathan :) You can mark as solved now

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