String data type

• A String is a sequence of one or more characters enclosed with in single apostrophe ' ' or double apostrophe " "

• In python we don't have CHAR data type

• A python string may contins any characters

Example:

>>>username="David"
>>>email='dwalker@mail.com'

each character of a python string contains +ve and -ve index values as shown

1. String slicing
2. String handling method

String slicing

retriving some portion of a given string

example :-

>>>x = "COMPUTER"

String handling method

There are many string handling following are most widely used string handling methods

1. capitalize(): Converts the first character to upper case

>>>user="python"
>>>print(user.capitalize())
Python



2. lower(): Converts string into lower case

>>>user="PYTHON
>>>print(user.lower())
python



3. upper(): Converts string into upper case

>>>user="python"
>>>print(user.upper())
PYTHON



4. find(): returns index of the first occurrence of a substring in a main string.
   
   if substring not found then returns -1.

>>>mystr="This is python"
>>>print(mystr.find('is'))
2
>>>print(mystr.find('Is'))
-1 #python is case sensitive
>>>print(mystr.find('was'))
-1



5. count(): use this method to count how many times a sub string has occured in the main string

>>>mystr="Python is simple,Python is awesome,python is easy'
>>>print(mystr.count('Python'))
2
>>>print(mystr.count('python'))
1 



6. replace(): use this method to replace one substring with another substring.

>>>mystr="This is core python"
>>>print(mystr.replace('core','advance'))
This is advance python 



7. split(): use this method to divide one into a list of multiple strings at a spliting characters.
   
   if the spliting character is not provided then by default it will split at white-space.

>>>mystr="python is simple;python is awesome"
>>>print(mystr.split(';'))
['python is simple' ; 'python is awesome']

>>>mystr="python is simple'
>>>print(mystr.split())
['python' , 'is' , 'simple'] 



8. join(): use this method to join a list of strings into a single string with a given string

>>>lst=['python' , 'is' ,'simple' ]
>>>print('->'.join(lst))
python->is->simple
>>>print(''.join(lst))
python is simple 



9. startswith(): use this method to check weather a main string starts with a given substring or not.
   If yes then returns True otherwise returns False

>>>username="David Walker"
print(username.startswith("david')
False
print(username.startswith("David")
True 



10. endswith(): use this method to cheack weather a main string ends with a given substring or not.
    If yes then returns True otherwise returns False

>>>username="David Walker"
print(username.endswith("walker")
False
print(username.endswith("Walker")
True 



11. strip(): use this method for removing white-space at before start of the value or end of the value.

>>>mystr="   David Walker   "
>>>print(mystr)
#white-space at start & end of the value
    David Walker   
>>>print(mystr.strip())
David Walker 

Note: To remove white-space only form left side then call lstrip() and to remove only from right side then call rstrip()


12. isalpha: Returns True if all characters in the string are in the alphabet

>>>mystr="CompanyX"
>>>print(mystr.isapha())
True



13. isdigit(): Returns True if all characters in the string are digits

>>>dig=20334
>>>print(dig.isdigit())
True



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