Python Tutorial: String Methods & Function

Saturday, 15 August 2020

String Methods & Function

 Python String Methods

Method

Description

capitalize()

Converts the first character to upper case

Example:

>>> 'true'.capitalize()

'True'

>>> 'language python'.capitalize()

'Language python'

len()

Returns length of string.

Example:

>>> s='Python Language'

>>> len(s)

15

>>> len("International")

13

count()

Returns the number of times a specified value occurs in a string

Syntax

string.count(value, start, end)

Parameter Values

value-Required. A String. The string to value to search for

start-Optional. An Integer. The position to start the search. Default is 0

end-Optional. An Integer. The position to end the search. Default is the end of the string

Example:

>>> str1="This is Python string class and this in interesting."

>>> value="is"

>>> print("This string 'is'occurs :",str1.count(value))

This string 'is'occurs : 3

>>> print("This string 'is'occurs :",str1.count(value,10))

This string 'is'occurs : 1

find()

Searches the string for a specified value and returns the position of where it was found

Syntax

string.count(value, start, end)

Parameter Values

value-Required. A String. The string to value to search for

start-Optional. An Integer. The position to start the search. Default is 0

end-Optional. An Integer. The position to end the search. Default is the end of the string

Example

>>> str1="This is Python string class and this in interesting."

>>> value="is"

>>> print("This string 'is'occurs :",str1.find(value))

This string 'is'occurs : 2

>>> print("This string 'is'occurs :",str1.find(value,10))

This string 'is'occurs : 34

format()

Formats specified values in a string

Example:

>>> txt1 = "My name is {fname}, I'am {age}".format(fname = "John", age = 36)

>>> txt1

"My name is John, I'am 36"

>>> txt2 = "My name is {0}, I'am {1}".format("John",36)

>>> txt2

"My name is John, I'am 36"

>>> txt3 = "My name is {}, I'am {}".format("John",36)

>>> txt3

"My name is John, I'am 36"

index()

Searches the string for a specified value and returns the position of where it was found

Example:

>>>txt = ”Hello, welcome to my world.”
>>>x = txt.index("e", 5, 10)
>>>print(x)

isalnum()

Returns True if all characters in the string are alphanumeric

Example:

>>> s=“CBSEExam2020”

>>> print(s.isalnum())

True

>>> s=“CBSEExam-2020”

>>> print(s.isalnum())

False

isalpha()

Returns True if all characters in the string are in the alphabet

Example:

>>> s=“Python”

>>> print(s.isalpha())

True

>>> s=“Python 3.8.3”

>>> print(s.isalpha())

False

isdigit()

Returns True if all characters in the string are digits

Example:

>>> s="CBSE2020"

>>> s.isdigit()

False

>>> s="2020"

>>> s.isdigit()

True

>>> s="CBSE-2020"

>>> s.isdigit()

False

islower()

Returns True if all characters in the string are lower case

Example

>>> s="cbse"

>>> s.islower()

True

>>> s="CBSEBOARD"

>>> s.islower()

False

isnumeric()

Returns True if all characters in the string are numeric

Example:

>>> s="2020"

>>> s.isnumeric()

True

>>> s="CBSE2020"

>>> s.isnumeric()

False

>>> num=2020

>>> num.isnumeric()

Traceback (most recent call last):

  File "<pyshell#22>", line 1, in <module>

    num.isnumeric()

AttributeError: 'int' object has no attribute 'isnumeric'

isupper()

Returns True if all characters in the string are upper case

Example:

>>> s=“cbse"

>>> s.isupper()

False

>>> s="CBSEBOARD”

>>> s.isupper ()

     True

join()

Joins the elements of an iterable to the end of the string

Example:

1.   Connecting elements using an empty string

>>> array = ['H','E','L','L','O']

>>> connector = ""

>>> joined_string = connector.join(array)

>>> print(joined_string)

HELLO

2.   Connecting using a comma

>>> array = ['1','2','3','4','5']

>>> connector = ","

>>> joined_string = connector.join(array)

>>> print(joined_string)

1,2,3,4,5

3.   Connecting without declaring a separate string variable

>>> array = ['W','O','R','L','D'] #

>>> print("-".join(array))

W-O-R-L-D

lower()

Converts a string into lower case

Example:

>>> s="CBSE2020"

>>> s.lower()

'cbse2020'

>>> s="CBSE board"

>>> s.lower()

'cbse board'

upper()

Converts a string into upper case

Example:

>>> s="CBSE board"

>>> s.upper()

'CBSE BOARD'

>>> s="cbse board 2020"

>>> s.upper()

'CBSE BOARD 2020'

partition()

Returns a tuple where the string is parted into three parts

Example:

# Split the string on 'and'

>>> S = 'Do it now and keep it simple'

>>> x = S.partition('and')

>>> print(x)

('Do it now ', 'and', ' keep it simple') # If the separator is not found

>>> S = 'Do it now and keep it simple'

>>> x = S.partition('or')

>>> print(x)

('Do it now and keep it simple', '', '')

>>> S = 'Do it now and keep it simple'

>>> x = S.partition('it') # If the separator is present multiple times, the method splits the string at the first occurrence

>>> print(x)

 ('Do ', 'it', ' now and keep it simple')

replace()

Returns a string where a specified value is replaced with a specified value

Example:

 

strip()

Returns a trimmed version of the string

Example:

>>> S = 'xxxxSxxxxSxxxx'

>>> x = S.strip('x')

>>> print(x)

 SxxxxS

>>> S = '... - Version 3.2 Model-32 ...'

>>> x = S.strip('.- ')

>>> print(x)

Version 3.2 Model-32

lstrip()

Returns a left trim version of the string

Example:

>>> S = 'xxxxSxxxxSxxxx'

>>> x = S.lstrip('x')

>>> print(x)

SxxxxSxxxx

>>> S = '... - Version 3.8 Model-32'

>>> x = S.lstrip('.- ')

>>> print(x)

Version 3.2 Model-32

rstrip()

Returns a right trim version of the string

Example:

>>> S = 'xxxxSxxxxSxxxx'

>>> x = S.rstrip('x')

>>> print(x)

xxxxSxxxxS

split()

Splits the string at the specified separator, and returns a list

Example:

>>> s="cbse board 2020"

>>> s

'cbse board 2020'

>>> s.split('board')

['cbse ', ' 2020']                    #converts into list

>>> s.split(' ')

['cbse', 'board', '2020']          #converts into list

swapcase()

Swaps cases, lower case becomes upper case and vice versa

Example:

>>> s="Swap Case of all Characters in a String"

>>> s.swapcase() 

'sWAP cASE OF ALL cHARACTERS IN A sTRING'

title()

Converts the first character of each word to upper case

Example:

>>> S = 'hello, world!'

>>> x = S.title()

>>> print(x)

Hello, World!

>>> S = "c3po is a droid"

>>> x = S.title()

>>> print(x)

C3Po Is A Droid

>>> S = "they're bob's friends."

>>> x = S.title()

>>> print(x)

They'Re Bob'S Friends
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