FOR LOOP
=========
==> HERE: for is the keyword
==> TO PERFORM SOME ACTION USING THE BLOCK OF CODE ON EACH INDIVIDUAL ELEMENT OF THE GIVEN/DEFINED COLLECTION, FOR LOOP CAN BE USED.
==> HERE, THE COLLECTION CAN BE:
	STRING, LIST, TUPLE, SET, BYTES, DICTIONARY ETC.

EX: [1,2,3,4,5,6,7,8,9]
EVEN ELEMENTS FROM THE ABOVE LIST
CONDITION: ELEMENT % 2 == 0 
1 % 2 == 0 ==> False
2 % 2 == 0 ==> True
3 % 2 == 0 ==> False

Syntax:
=====
	for iteration_variable in collection_data:
		statement-1
		statement-2

Here:
	like while loop, 
		no intialization is used
		no condition is used
		no update is used.
in for loop:
	first element of the specified collection ==> start point of the for loop
	last element of the collection ==> end point of the for loop
	update ==> is not required.

len()
===
==> used to find the size of any collection
Syntax:
	len(collection_name)

# WRITE A PYTHON PROGRAM TO PRINT THE INDIVIDUAL ELEMEMNTS OF THE GIVEN STRING ALONG WITH ITS POSITIVE AND ITS NEGATIVE INDEX ALSO.

"""
STR_DATA = "PYTHON"

EXP_OP:

THE CHARACTER AT POSITIVE INDEX 0 AND AT NEGATIVE INDEX -6 = P
THE CHARACTER AT POSITIVE INDEX 1 AND AT NEGATIVE INDEX -5 = Y
"""

str_data = input("Enter a string data:")

# using positive index

index = 0

for i in str_data:
    # print("The Character at positive index",index,"is =",i)
    # print("The Character at negative index",index-len(str_data),"is =",i)
    print("The Character at positive index",index,"and at negative index",index-len(str_data),"is =",i)
    index += 1
print()

# using negative index
index = -1

for j in str_data[::-1]:
    print("The Character at negative index",index,"is =",j)
    index = index - 1

==============================
to define a collection in run time:
eval()
====
input()
====
Syntax:
	eval(input())

# WRITE A PROGRAM IN PYTHON TO FIND THE SUM OF ALL ODD ELEMENTS OF THE GIVEN LIST

"""
1) DEFINE A LIST
2) FIND ALL ODD ELEMENTS
3) PERFORM SUM ON ODD ELEMENTS
4) PRINT THE SUM
"""

list_data = eval(input("Enter a list data:"))

sum_odd = 0

for i in list_data:
    if i % 2 != 0:
        sum_odd = sum_odd + i

print("The sum of all odd elements of a list = ",sum_odd)

===================================

==> for loop is also able to define the block of action on individual element/value of the certain range of values.
==> range() ==> we can able to generate range of values
Syntax:
	1) range(value) ==> generate a values from 0 (by default) to value-1
	2) range(start, stop) ==> generate values from 'start' to 'stop-1'
	3) range(start, stop, step) ==> generate values from 'start' to 'stop-1' with the difference of 'step'

# WAP IN PYTHON TO PRINT ALL FACTORS OF 11 FROM 100 TO 500.

"""
1) we should define the range for finding factors of 11
2) we should make a logic for checking factors of 11
"""

# print(range(10))
# print(range(10,20))
# print(range(10,20,2))

# a = range(10)
# b = range(10,20)
# c = range(10,20,2)
#
# print(a)
# print(b)
# print(c)

for i in range(100,500):
    if i % 11 == 0:
        print(i,end = "\t")

# WAP TO PRINT ALL EVEN NUMBERS FROM 500 TO 100.

# for i in range(500,399,-1):
#     if i % 2 == 0:
#         print(i,end = "\t")

for i in range(500,399,-2):
    print(i,end = " ")


NESTED LOOPS
==============
OUTER_LOOP:
	INNER_LOOP:
		ST-1
		ST-2
	ST_3
	ST_4

WHILE:
	FOR:

FOR: 
	WHILE:
WHILE:
	WHILE
FOR:
	FOR

# WAP IN PYTHON TO PRINT ALL PALINDROME NUMBERS FROM 1000 TO 2000

"""
PALINDROME NUMBER:
    REVERSE_NUM == NUMBER

1) WE SHOULD DEFINE RANGE FOR 1000 TO 2000
2) WE WRITE A LOGIC FOR FINDING THE REVERSE
"""

for p in range(1000,2001):
    n = p   # initialization
    rev_num = 0
    while n != 0:
        ind_dig = n % 10
        rev_num = rev_num * 10 + ind_dig
        n //= 10    # update

    if rev_num == p:
        print(p,end = "\t")

===========================

# WAP IN PYTHON TO PRINT ALL ARMSTRONG NUMBERS FROM 9999 TO 1000 (4-DIGIT)

"""
ARMSTRONG NUMBER:
    SUM OF NTH POWERS OF INDIVIDUAL DIGITS == ORIGINAL NUMBER

9999 ==>   9^4 +  9^4 + 9^4 +  9^4 == 9999
371 ==> 3^3 + 7^3 + 1^3 == 371
"""

for arm in range(9999,1000,-1):
    n = arm
    sum_powers = 0
    while n > 0:
        ind_dig = n % 10
        powers = ind_dig ** 4
        sum_powers = sum_powers + powers
        n //= 10

    if sum_powers == arm:
        print(arm,end = "\t")

========================================

ASSIGNMENTS:
=============
1) WAP IN PYTHON TO PRINT ONLY EVEN POSITIONED CHARACTERS OF THE GIVEN STRING.
"PYTHON"
P
T
O
2) WAP TO PRINT ALL THE INDIVIDUAL ELEMENTS OF THE TUPLE ALONG WITH POSITIVE AND NEGATIVE INDEX.
3) WAP IN PYTHON TO PRINT ALL THE PRIME NUMBERS FROM 100 TO 500.