Merge pull request #19 from seancyw/issue_9

Added program to find factorial of number #9

Author: HarendraSingh22

Code/factorial.py

@@ -1,16 +1,16 @@
-def get_factorial(number):
-    answer = 1  # We start with 1 as usual for finding factorial
-    
-    for i in range(1, (number+1)):  # 1 is added to second argument of range function since it in this syntax loop terminates at the second value without executing for that value.
-        answer = answer * i
-
-    return answer # answer now contains the calculated value
-
-
-
-if __name__ == '__main__':
-    number = input("Enter the number : ")
-    number = int(number)
-    factorial = get_factorial(number)
-    print ("The factorial of " + number+ " is = " + factorial)
-
+
+#program to find the factorial of a number provided by a user
+
+if __name__ == "__main__":
+    number = int(raw_input("Enter a number to get its factorial: "))
+    factorial = 1
+
+    if number < 0:
+        print("Sorry, factorial doesn't exist for negative numbers!")
+    elif number == 0:
+        print("The factorial of 0 is 1")
+    else:
+        for i in range(1, number + 1):
+            factorial = factorial * i
+        print "The factorial of %r is %r" % (number, factorial)
+