String Manipulations
				====================
What is a string?
=================
-> a group of characters which enclosed with quotes is called as a "string".
-> In python:
	the string can define with:
		single quotes
		double quotes
		triple quotes

Note:
=====
In other languages like java:
	have character data representation
		character ==> 'a'
But, python does not support the character representation, the character representation like other languages in python considered as "string".

Syntax for the string definition is:
	variable-name/identifier = 'group of characters' or "group of characters"

==> "str" is the class name for the strings.

# string definition

s1 = 'a'    # characters are: alphabets, digits, special characters (,./?@!
s2 = 'python'
s3 = "2"
s4 = "python3"

print(type(s1))
print(type(s2))
print(type(s3))
print(type(s4))

s5 = ('Hi'
      'Good morning.'
      'Today we are learning'
      'about strings.')
s6 = ("Hello"
      "Good morning."
      "Today, we are going to learni"
      "about the strings Introduction.")

print(s5)
print(s6)

# for multi-line string: we can use triple quotes

s7 = '''Hi
today, we have started
about the string introduction'''

s8 = """Hi
Welcome to Ashok IT.
We are providing various IT Skill and courses
as per industry demands."""

print(s7)
print(s8)

s9 = "I am learnong 'python' for my 'AWS Devops' interview purpose."
s10 = "I am learnong \"python\" for my \"AWS Devops\" interview purpose."

# in general, we cannot write double quotes within double quotes or single quotes
# within single quotes.
# but we can define double quotes within single quotes or vice versa.
# if you want to define the double quotes within the double quotes (nesting of quotes)
# in this case, the inner quotes must be prefixed with \

print(s9)
print(s10)

==================================================
How to access the string characters?
====================================
-> there are two ways:
	1) using indexing
	2) using slicing
	3) using loop statements

1) using Indexing:
==================
-> Index ==> is representing with integer value
Index can use to get the substring from the main string.
"Python" ==> 'P', 'y', 't', 'h', 'o', 'n' (sub-strings)
-> substring ==> part of string
-> to acquire the character/sub-string from the main string, we can use index
-> that every character in a string can be uniquely represented with a number is called as an "index".
-> The indexing is define with two ways:
	1) Positive indexing
	2) Negative indexing
-> Positive indexing can use to access the characters of the string from left to right direction. This approach is called as "Forward accessing".
-> Positive indexing can start with: '0' and end with 'n-1'
	Here: n ==> number of characters of the string
Ex: string with 10 characters:
	range for the positive indexing ==> 0 to 9
Syntax for string indexing is:
	string-name[index]

Ex: s = "python"
s[0] ==> 'p'
s[1] ==> 'y'
s[2] ==> 't'
s[3] ==> 'h'
s[4] ==> 'o'
s[5] ==> 'n' 

s = "Python"

print(s[0])
print(s[1])
print(s[2])
print(s[3])
print(s[4])
print(s[5])

-> Negative indexing can define with negative range of index values
can use to access the characters from right to left. This kind of access is called as "Reverse accessing".
-> Negative indexing can be ranged from:
	-1 to -n
here:
	n ==> number of characters of string
Ex: string with 10 characters:
	negative index range ==> -1 to -10

s = "Python"

print(s[-1])
print(s[-2])
print(s[-3])
print(s[-4])
print(s[-5])
print(s[-6])
 
Note:
=====
1) When we define the index which is out of range, then we can get error "Index Error"
Here: Index error ==> Run time error.
2) Python can understand the positive index only by default.

=====================================================
Looping on strings:
===================

using while loop:
=================

# while loop

# WAP TO ACCESS ALL THE CHARACTERS OF THE GIVEN STRING USING ITS POSITIVE AND NEGATIVE INDEX ALSO.

"""
HINT:
s = "Python"

the character at positive index '0' and negative index -6' ==> 'P'
"""
s = "High-level"

index = 0   # initialization
while index < len(s): # condition
    print("The Character at positive index",index,"and at negative index",index-len(s),"is = ",s[index])
    index = index + 1   # update