STRING OPERATIONS:
==================
MATH OPERATIONS ON STRING DATA:
===============================
1) STRING CONCATENATION
========================
==> JOINING OF TWO OR MORE STRINGS INTO ONE STRING IS CALLED AS STRING CONCATENATION.
EX: "PYTHON"
"PROGRAMMING"
CONCATENATION RESULT ==> "PYTHONPROGRAMMING"
==> SYMBOL: '+'
Syntax:
	str-data1 + str_data2

Rule:
=====
String concatenation in python is always with string data.

# STRING CONCATENATION

str1 = "python"
str2 = "programming"
a = 9779

print("The String Concatenation Result = ")
print(str1 + str2)
print(str2 + str1)
# print(str1+str2+a)

2) STRING REPETITION
=====================
Repeating the content of the string data for number of times is called as "string repetition"
==> symbol: '*'

Syntax:
	str-object * n

str1 = "python"

print("The Result of String Repetition is = ")
print(str1 * 7)

Mutability Vs Immutability:
===========================
Immutability:
=============
integer, float, complex
Boolean
String
	====> Immutable Datatypes

Once the data definition is completed, we cannot modify that definition.

# Immutability

a = 1212
b = 123.123
c = 123-234j
d = True
e = 'abcde'

print("The Addresses of the given data are:")
print(id(a),id(b),id(c),id(d),id(e))

# define the change

a = 1234
b = 123.987
c = 123+234j
d = False
e = 'Python'

print("The Addresses of the given data are:")
print(id(a),id(b),id(c),id(d),id(e))

Mutability:
===========
After the definition, the data can consider to modify within the same address location.

Ex: List, Set, Dictionary etc.


Is String Immutable?
====================

str1 = "python"
str2 = "programming"

print(id(str1))
str1 = str1 + str2
print(str1)
print(id(str1))
str1 = str1.upper()
print(str1)
print(id(str1))

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

Membership Check on String data:
================================

str1 = "Python Programming"

print('Pro' in str1)
print('program' in str1)

print('Pro' not in str1)
print('program' not in str1)

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

String Comparison:
==================
Python2:
=======
we had a method:
cmp()
====
Syntax:
	cmp(o1,o2)
		return:
			1 ==> o1 > o2
			-1 ==> o1 < o2
			0 ==> both objects are equal/same

s1 = "Python"
s2 = "python"

print(cmp(s1,s2))
print(cmp(99,79))

# Unicode :
# a to z ==> 97 to 122
# A to Z ==> 65 to 90
# 0 to 9 ==> 48 to 56

Note:
====
cmp() got deprecated from Python-3.

for the string comparison ==> we can use "relational operators". 

s1 > s2 ==> True/False

# String Comparison

s1 = "python"
s2 = "python"
s3 = "pyThon"

print(s1 == s2)
print(s1 == s3)

print(s1 > s2)
print(s1 < s2)

print(s1 > s3)
print(s1 < s3)

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

Removing of spaces from the string
==================================
1) strip()
==========
==> An inbuilt method, which we can use to remove the spaces from left and right side of the string.
"   Python"
"Python   "
"   Python    "
strip() ==> "Python", "Python", "Python"
Syntax:
	str-object.strip()

# Removing of spaces from the string

str1 = "Python   "
str2 = "   Python"
str3 = "   Python   "

print(str1)
print(str2)
print(str3)

print(str1.strip())
print(str2.strip())
print(str3.strip())
 
2) rstrip():
============
an inbuilt method which we can use to remove the spaces from the right side of the given string

Syntax:
	str-object.rstrip()

# Removing of spaces from the string

str1 = "Python   "
str2 = "   Python"
str3 = "   Python   "

print(str1)
print(str2)
print(str3)

print(str1.rstrip())
print(str2.rstrip())
print(str3.rstrip())

3) lstrip()
===========
is an inbuilt method which we can use to remove the spaces from left side of the string.
Syntax:
	str-object.lstrip()

# Removing of spaces from the string

str1 = "Python   "
str2 = "   Python"
str3 = "   Python   "

print(str1)
print(str2)
print(str3)

print(str1.lstrip())
print(str2.lstrip())
print(str3.lstrip())

Note:
====
Spaces between the string cannot be removed.
"Python Programming".strip() ==> "Python Programming"

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

Counting of Substrings from the given string:
=============================================
To count the number of occurrences of the given sub-string in a given string, we can use count() method.

Syntax:
	str-object.count('sub-string')
return: '0', when the sub-string is not in the given string.
return: number of occurrences, when the sub-string is in the given string.

# Sub-string count

st1 = "Python Programming"

count1 = st1.count('P')
count2 = st1.count('p')
count3 = st1.count('m')
count4 = st1.count('mm')

print(count1)
print(count2)
print(count3)
print(count4)

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

Finding of sub-strings
======================
Fining of sub-strings from left to right of the string is considered as "Forward finding"
Finding of sub-strings from right to left of the string is considered as "Backward finding".

Forward Finding:
================
find()
=======
Syntax:
	str-object.find('sub-string')

# find() Vs index()

str1 = "Python Programming"

# if the sub-string is at one place
print(str1.find('h'))

# if the sub-string is at multiple places, find() can return the first index value (occurrence)
print(str1.find('n'))

# if the sub-string is not in the given string, find() can return "-1"
print(str1.find('-'))

index()
=======
Syntax:
	str-object.index()

# find() Vs index()

str1 = "Python Programming"

# if the sub-string is at one place
print(str1.index('h'))

# if the sub-string is at multiple places, index() can return the first index value (occurrence)
print(str1.index('n'))

# if the sub-string is not in the given string, index() can return "Value Error"
print(str1.index('-'))

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

Reverse Finding:
================
rfind()
=======
Syntax:
	str-object.rfind()

rindex()
========
Syntax:
	str-object.rindex()