new code

Basic Python Pratice Program/14_Factorialiterative.py

@@ -1,24 +1,29 @@
-""" This is a program to calculate the factorial of a number using a for loop and a while loop. """
+""" This program calculates the factorial of a number using different methods. """
 
-def factorial_for(n):
-    """ This function calculates the factorial of a number using a for loop. """
+def factorial(n):
+    """ This function calculates the factorial of a number using an iterative approach. """
+    if n < 0:
+        raise ValueError("Factorial is not defined for negative numbers.")
     result = 1
-    for i in range(1, n+1):
+    for i in range(2, n + 1):  # Start from 2 to avoid unnecessary multiplications
         result *= i
     return result
 
 def factorial_while(n):
     """ This function calculates the factorial of a number using a while loop. """
+    if n < 0:
+        raise ValueError("Factorial is not defined for negative numbers.")
     result = 1
     while n > 1:
         result *= n
         n -= 1
     return result
 
 def main():
-    """ This is the main function. """
-    print(f"factorial_for(5) = {factorial_for(5)}")
-    print(f"factorial_while(5) = {factorial_while(5)}") 
+    """ The main function to demonstrate the factorial calculations. """
+    test_value = 5
+    print(f"factorial({test_value}) = {factorial(test_value)}")
+    print(f"factorial_while({test_value}) = {factorial_while(test_value)}")
 
 if __name__ == "__main__":
-    main()
+    main()