Advanced Functions
==================
Types of Variables
==================
-> two types:
	1) Local Variables
	2) Global Variables

Local Variables
===============
-> Local variables are also called as "function variables".
-> The local variable have the scope within the function.
Ex:
def function():
	x = 10
	print(x)
print(x) ==> Name error

def greetings():
    name = "Ajay" #local variable
    print("Hello",name,",Good Evening!")

greetings()
# print("Hello",name,",Good Evening!")
def wishes(name):
    print("Hi,",name)
wishes("Rk")

Note:
=====
Python does not support the block variable scope, because it is a dynamically typed language.

def f1():
    if(True):
        x = 123
        print(x)
    if(1):
        print(x)
    print(x)
f1()
# print(x)

Mutability Vs Immutability
==========================
x = 100
y = x # original definitions

print(x)
print(y)

print(id(x))
print(id(y))

x = 200 # re-assignment/ modification
print(x)
print(y)
print(id(x))
print(id(y))

a = [1,3,4,5]
print(id(a))
a[2] = 123
print(a,id(a))
a = [1,2,3,4]
print(id(a))

Global Variables
================
-> We can define a variable in outside the function
and allowed to access in anywhere within the program.

x = 123
def f1():
    print(x)
    print(y)
def f2():
    print(x)
    print(y)
def f3():
    print(x*x)
    print(y)
print(x)
y = 321
f1()
f2()
f3()
print(y)

Q-1:
====
is it possible to define a global variable in inside the function?
===================================================================
Ans: Yes.
using 'global' keyword

def f1():
    global x    # declaring a global variable
    x = 123
    print(x)
# print(x)
f1()
print(x)

Q-2:
is it possible to modify the global variable in function?
Ans: Yes
using global keyword

a = 100 # global variable
def f1():
    # print(a)
    global a
    a = 200
    print("Inside the function:",a)
print("Outside the function:",a)
f1()
print("After the modification:",a)
==================================================
Recursion:
==========
the function that calls itself is called "Recursion".


Factorial of number using loops:
================================
n = int(input("Enter a value:"))

i = n
factorial = 1
while i != 0:
    factorial = factorial * i
    i = i - 1
print(factorial)

using functions:
================
def factorial(n):
    fact = 1
    if n == 0:
        print("Factorial = ",fact)
    elif n > 0:
        i = n
        while i != 0:
            fact = fact * i
            i = i - 1
        print("Factorial = ",fact)
    else:
        print("Factorial is not possible")
factorial(5)
============================================
using Recursion:
================
def factorial(n):
    if n == 0:
        fact = 1
    else:
        fact = n * factorial(n-1)
    return fact

result = factorial(5)
print(result)