FUNCTIONS:
==========
Function is a named block
	can be used to perform the block of action.

ex: Ecommerce Application
	search option
	cart
	payment etc.

==> to define the functions in python:
	keyword: def
==> the functions can have three things:
	1) function definition
		1) Function header
		2) function body
	2) function call
==> function can accept the data with respect to parameters
	and perform the action on that data
	and return a value.

Syntax: (for function definition)
	def function-name/identifier(parameters/arguments-name):
		statement-1
		statement-2
		return value

Syntax: (for function calling/invoking)
	function-name(values for the parameters)

==> functions can be defined in 4-ways:
	1) function without parameters and no return type
	=================================================

# function without parameters and no return type

def ecart_total():
    cart_items = [199,399,348,1999,999,899,789,648,123] # group/collection
    sum_items = 0
    index = 0
    for item in cart_items:
        sum_items = sum_items + item
        print("The product",index+1,"is = ",cart_items[index])
        index = index + 1

    print("The Total Amount = ",sum_items)

ecart_total()

	2) function without parameters and return type
	==============================================

# function without parameters and return type

# WAP TO CREATE A FUNCTION IN PYTHON TO REVERSE THE STRING.
# string[::-1]

def reverseString():
    str_data = input("Enter a string:")

    str_reverse = ""

    for ch in str_data:
        str_reverse = ch +  str_reverse
    return str_reverse

result = reverseString()
print("The Reverse of the string = ",result)
================================================================

	3) function with parameters and no return type
	==============================================

# FUNCTION WITH PARAMETERS AND NO RETURN TYPE

def ecart_total(list_products):
    sum_product = 0
    index = 0
    for item in list_products:
        sum_product += item
        print("Product",(index+1),"is = ",list_products[index])
        index += 1
    print("The Total Amount = ",sum_product)

cart_items = [199,399,349,1999,599,899,1299,1099,999]
ecart_total(cart_items)

=======================================================
	4) function with parameters an return type
	===========================================

# Function With Parameters and return type

def greets(name):
    wish = "Good Evening {}".format(name)   # "good evening",name
    return wish

print(greets("Ravi"))

====================================================
Function Parameters:
====================
==> four ways to define parameters in function.
	1) Positional arguments
	2) Keyword arguments

# positional Arguments

def addingNumbers(a,b,c):
    s_numbers = a+b+c
    print("The Sum of three numbers = ",s_numbers)

addingNumbers(121,131,1021) # positional arguments
# Keyword Arguments
x = 1021
y = 1321
z = 1993
addingNumbers(c = x,a = z,b = y)
addingNumbers(a = 100,b = 200,c = 300)

	3) Default Arguments
	=====================

ef SumOfNumbers(a = 0,b = 1,c = 2,d = 3):
    print("The Sum = ",a+b+c+d)

SumOfNumbers()
SumOfNumbers(10)
SumOfNumbers(10,20)
SumOfNumbers(100,200,300)
SumOfNumbers(100,200,300,400)

	4) Variable Length Arguments
	=============================

# Variable Length Function

def SumOfNumbers(*args):# args = (10,30,50)
    s_num = 0
    for i in args:
        s_num += i
    print("The Sum = ",s_num)

SumOfNumbers()
SumOfNumbers(10,30,50)
SumOfNumbers(199,299,399,499,599,699,799,899)

===========================================================
1) WAP TO CREATE THE FUNCTION IN PYTHON TO PRINT ALL ARMSTRONG NUMBERS FROM 1000 TO 10000.
2) WAP TO CREATE THE FUNCTION TO FIND THE FACTORIAL OF THE NUMBER.
3) WAP TO CREATE THE FUNCTION TO PRINT ALL PRIME NUMBERS FROM 100 TO 200.
4) WAP TO CREATE THE FUNCTION TO PRINT MULTIPLICATION TABLE FOR THE GIVEN NUMBER.