Python String Handling

Basics of Python Strings.

A Python string is a sequence, which consists of zero or more characters.
The string is an immutable data structure, which means they cannot be changed.

String Function

Len function: In order to find the length of the string. Ex len(string variable).
The subscript operator([]):It is used to access the elements of string, list tuple, and so on.

Syntax: <given string>[index].

The -1 index represents the last character

Slicing for substrings

In many situations, you might need a particular portion of strings such as the first three characters of the string.
Python’s subscript operator uses slicing.
In slicing, colon : is used. An integer value will appear on either side of the colon.
print(name[0:4])
print(name[23])
print(name[0:-1])
print(name[:8])
print(name[::2])

Python string methods:

Count Function:The count method returns the number of occurrences of the substring substr in string
Find Method: The find() method is used to find out whether a string occurs in a given string or its substrings.
find method will only give the index of the first occurrence.
If you want to find the occurrence from right, you can use the rfind method.

String case methods

lower() method.
upper() method
capitalize() method:capitalize the first character of the line.
Title method: convert the first character of every word of the string in uppercase.
A swapcase method allows the user to swap the cases:

String strip methods

Dealing with the strings, many times programmers encounter the problem of undesirable character/characters at the end or beginning of the string, such as space or new line character at the end, for example, ” Baba saheb ” and “Dr Ambedkar n”.
To handle these problems, the Python string class comes loaded with three methods.
Rstrip method:unwanted character/characters get removed from the r
If you do not provide any chars as argument, then space is taken as default. right side of the string.
If you want to strip from the left-side use the lstrip() method. If you want to strip from both sides, use the strip() method.

String split methods

Sometimes we see strings in the form of parts.
based upon delimiters, we can split strings into parts and take the desirable part.

Syntax :Str1.split(“delimiter”, num)

The split method returns a list of all the words of the string separated by a delimiter and the num integer specifies the maximum splits.
If you don’t provide any delimiter, then the space is taken as the default.
If you want that splits should be started from the right, then you can use the rsplit()

Some special methods of string

Replace : This method returns a copy of the string in which the old character(s) are replaced with new character(s).
Join Method : Consider you have a sequence (list or tuple) of string and you want to join values of the sequence.

String Boolean Method

return the value in the form of True or False based upon certain conditions.
Endswith method: Sometime we are interested in strings which are ends with particular substring. For this we use string method endswith()
Startwith method:which works the same way as the previous method, just check the condition from the beginning.
Isalpha method: assure that the given string must contain only letters.blank spaces are not allowed.
isalnum() method : check the alphanumeric characters appearing in the string. This method returns True if the string contains only alphanumeric characters like hello123 allowed but hello123# is not allowed. Blank space are not allowed
Isdigit method: If you only want to check digits, then you can use the isdigit() method
isspace(), which returns True if the string contains only spaces
The istitle() method returns True if the string is in title case.
Islower()- Check Lower Case
IsUpper()- Check Upper Case
Min():The min() function returns the min character from string str1 according to the ASCII value.
Max():which returns the max characters from string str according to the ASCII value

All Example:

"""import ctypes
name = 'yogesh sharma'
# Store Address
nameaddress = id(name)
# Print Address
print(id(name))
# Update String
name = 'vikas sharma'
# memory address will be changed
print(id(name))
# Get Value of Memory Address
name2 = ctypes.cast(nameaddress,ctypes.py_object).value
print(name2)"""
# Slicing Function
"""name = 'yogesh'
print(len(name))
print(name[1])
print(name[5])
print(name[-1])
print(name[-6])"""
# Slicing for substring
"""name ='My Name is Yogesh Sharma'
print(name[0:4])
print(name[23])
print(name[0:-1])
print(name[:8])
print(name[::2])"""
# String Methods
"""name = "My Name is Yogesh sharma"
print(name.count('a'))
# Search Start Index
print(name.count('a',8,24))
print(name.find('Name'))
# TO Find first Index from right
print(name.rfind('m'))
# output
3
2
3
22
"""
# String Case Methods
"""name = 'My Name is yogesh sharma'
# Lower case
print(name.lower())
# Upper case
print(name.upper())
# Capatalize case
print(name.capitalize())
# Title method
print(name.title())
# Swap case
print(name.swapcase())
#Output
my name is yogesh sharma
MY NAME IS YOGESH SHARMA
My name is yogesh sharma
My Name Is Yogesh Sharma
mY nAME IS YOGESH SHARMA"""

# string Strip Methods
"""name = 'Yogesh Sharma'
print(name.rstrip('rma'))
# For Blank space from right side
name1 = '   vikas sharma    '
print(name1.rstrip())
# Strip from left side
print(name1.lstrip())
# Strip from both sides
print(name1.strip())

# Output
Yogesh Sh
   vikas sharma
vikas sharma    
vikas sharma
"""

# String split methods. Returns output in a list
mydate = '12-01-2007'
print(mydate.split('-',1))
# ['12', '01-2007']
print(mydate.split('-'))
# ['12', '01', '2007']
# get Value of list
newdatelist = mydate.split('-')

print(newdatelist[1])
# 01
# Without Deliminator
name2 = 'my name is yogesh sharma'
print(name2.split())
# ['my', 'name', 'is', 'yogesh', 'sharma']
# Rsplit Example
print(mydate.rsplit('-',1))
# ['12-01', '2007']
# replace method
name3 = 'Yogesh Sharma was a nice person'
print(name3.replace('was','is'))
#Yogesh Sharma is a nice person
# Maximum Replacements
name4 = 'Yogesh sharma was a nice person, his reputation was gud'
print(name4.replace('was','is',1))
# Yogesh sharma is a nice person, his reputation was gud
# Join Method Example
mylist=['yogesh','sharma']
print(''.join(mylist))
# Output - yogeshsharma
print('-'.join(mylist))
# Output - yogesh-sharma
print(' '.join(mylist))
# Output- yogesh sharma


# String Boolean Methods
# endswith method example - return True or false value only
name4 = 'My name is Yogesh sharma'
print(name4.endswith('rma'))
# Output - True
print(name4.endswith('pma'))
# Output - False
# To check upto particular Index Only
str1 = "Life should be great rather than long"
print(str1.endswith('er',0,27))
# output - True
# Startwith method
print(str1.startswith('Li'))
print(str1.isalpha())
# Output: False (Blank space are not allowed)
str2 = 'YogeshSharma'
print(str2.isalpha())
# Output = True
str3 = 'hello 123'
print(str3.isalnum())
#output -True
# isdigit method
str4 = '123'
print(str4.isdigit())
# Output = True
# isspace method
str5 = "hello   "
print(str5.isspace())
#Output-  False
str6 = ' '
print(str6.isspace())
# Output - True
#istitle method
str7 = 'My Name Is Yogesh Sharma'
print(str7.istitle())
# Output- True
# islower and isupper methods
print(str7.islower())
print(str7.isupper())

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