STRING OPERATIONS
=================
WHAT IS STRING?
===============
ANY TEXT
GROUP OF ANY CHARACTERS WHICH ENCLOSED WITH SINGLE QUOTES OR WITH DOUBLE QUOTES IS CALLED AS "STRING"
EX: 'PYTHON', "1234", 'PY@123'

NOTE:
====
IF A STRING CAN START WITH SINGLE QUOTE THEN IT SHOULD END WITH SINGLE QUOTE ONLY.
IF A STRING CAN START WITH DOUBLE QUOTES THEN IT SHOULD END WITH DOUBLE QUOTES ONLY.
EX: 'PYTHON" OR "PYTHON' ==> INCORRECT 

CHARACTERS FOR DEFINING THE STRING ARE:
	ALPHABETS ==> LOWER CASE, UPPER CASE	
	DIGITS ==> 0 TO 9	
	ANY SPECIAL CHARACTER (@,#$%^&}

ASCII Vs UNICODE:
=================
ASCII ==> AMERICAN STANDARD CODE INFORMATION INTERCHANGE

ASCII IS A STANDARD WHICH DESCRIBE SOME RULES TO DEFINE THE INTEGER NUMBER (ASCII VALUE) FOR EACH AND EVERY CHARACTER.

EX: A TO Z ==> 65 TO 90
a TO z ==> 97 TO 122
0 TO 9 ==> 48 TO 56

C/C++ ==> 
CHARACTER DATA ==> 1 BYTE ==> 8-BITS
WE CAN REPRESENT 2^8 NUMBER OF CHARACTERS ONLY
256 CHARACTERS ==> 0 TO 255

GLOBAL LANGUAGES
UNICODE:
=======
PYTHON IS UNICODE DEPENDENT LANGUAGE

JAVA:
CHARACTER DATA ==> 2-BYTES ==> 16-BITS
REPRESENT: 2^16 CHARACTERS ==> 65536 ==> 0 TO 65535

COMPUTERS ENCODE: UTF-16, UTF-32, UTF-64 ETC.

NOTE:
====
IN PYTHON, THERE IS NO CHARACTER DATA REPRESENTATION.
'A' ==> STRING
'ABC' ==> STRING

chr()
=====
==> is an inbuilt method, which we can use to return the character according to the UNICODE value.
Syntax:
	chr(Unicode)

ord():
=====
==> is an inbuilt method which we can use to return a Unicode value according to the Character value.
Syntax:
	ord(character)

len():
=====
==> is an inbuilt method which we can use to get the length of the string or any collection.
Syntax:
	len(string-name)

a = 'python'
b = "Python"
c = '1234'
d = "abc@123"
e = 'a'

print(type(a),type(b),type(c),type(d),type(e))

# Displaying of All Unicodes:

for i in range(65536):
    print("The Character at the Unicode {} is = {}".format(i,chr(i)))

# Accessing of Unicodes according to the character 

index = 0

while index < len(a):
    print("The Unicode of the character {} is = {}".format(a[index],ord(a[index])))
    index += 1

for k in a:
    print("The Unicode of character {} is = {}".format(k,ord(k)))

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

String is Index Based, Slicing Supported and Ordered
=====================================================
To access the individual character of the string we can use an index
Index ==> an integer

Note: In python, index can be with both: positive values and with negative values also.

Index can represent in two ways:
	1) Positive Indexing
	=====================
		==> It can always start with: '0'
		==> It can end with: len(str)-1
		==> The Characters of the string can access from left to right.
		Syntax:
			str-name[positive index]
ex:
a = 'Python'
a[0] ==> P
a[1] ==> y
a[2] ==> t
a[3] ==> h
a[4] ==> 0
a[5] ==> n
	2) Negative Indexing
	====================
		==> It can always start with: '-1'
		==> It can end with: -len(str)
		==> The characters of the string can access from right to left.
		Syntax:
			str-name[negative index]

ex: 
a = "python"
a[-1] ==> n
a[-2] ==> o
a[-3] ==> h
a[-4] ==> t
a[-5] ==> y
a[-6] ==> p

Slicing on Strings:
===================
accessing the part of the string
Syntax:
	str-name[start:stop:step]

Note:
====
In slicing:
	start, stop and step are optional
if start is not present ==> slicing can start from first character by default.
if stop is not present ==> slicing can stop at last character by default
if step is not present ==> difference can consider as '1' by default.

a = "python"
b = "Python Programming"

# positive indexing

print(a[0]);print(a[1]);print(a[2]);print(a[3]);print(a[4]);print(a[5])

print()

# negative indexing

print(a[-1]);print(a[-2]);print(a[-3]);print(a[-4]);print(a[-5]);print(a[-6])

# Slicing
print(b[0:6:1]);print(b[0:6]);print(b[:6:1]);print(b[:6:])
print(b[7:len(b):1]);print(b[7::1]);print(b[7::])

# start < stop ==> for slicing
# if start > stop ==> step as negative

print(b[-1:-15:-1])
print(b[15:0:-1])

print(b[::])
print(b[::1])   # forward slicing
print(b[::-1])  # reverse slicing

# ordered

print(a);print(b)

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

Multi-line String
=================
triple quotes ==> ''' ''' or """ """

'Python is 'High level'' ==> Incorrect

ms = '''Python is
High Level
Programming
Language'''

ms1 = """Python is 
Object Oriented 
Programming 
Language"""

ms2 = 'Python is \'High level\' programming langauge'
ms3 = "Python is \"Object Oriented\" Programming Language"
ms4 = 'Python is "Easy" Language'
ms5 = "Python  is 'Dynamically Typed' Language"

print(ms);print(ms1);print(ms2);print(ms3);print(ms4);print(ms5)