String in Python

What is string?

In Python, a consecutive sequence of characters, which are enclosed or surrounded by single (‘ ’) or double (“ ”) quotes, is known as string. This sequence of characters may include a letter, a number, special character or a backslash (\). Python Strings are immutable.

How to create a string in Python?

>>> str='String Tutorial'

>>> print(str)

String Tutorial

>>> str="Python Tutorial"

>>> print(str)

Python Tutorial

>>> my_string='''Work in Progress'''

>>> print(my_string)

Work in Progress

>>> my_string="""Work in Progress"""

>>> print(my_string)

Work in Progress

>>> my_string= """Work                       # triple quotes string can extend multiple lines

in

Progress"""

>>> print(my_string)

Work

in

Progress

>>> my_string="Tutorial on \"Python\" "  # using escape sequence \”

>>> print(my_string)

Tutorial on "Python"

>>> str1="Accessing string characters in new line\n Python"     # using escape sequence \”

>>> print(str1)

Accessing string characters in new line

 Python

>>> str1="Chapter :\t String"

>>> print(str1)

Chapter:      String

 

How to access characters in a string? Or Traversing a string

For example :

A= “COMPUTER”

We can start Index value either from left or from right. Left index starts from 0 and right-side index start from -1

For Example:

Str1= “PYTHON STRING”

 STR="Informatics"

for i in STR:

          print(i)

 

output:      

I

n

f

o

r

m

a

t

i

c

s

 

Special String operators

String can be manipulated using operators like concatenate (+), repetition (*), and membership operator like in and not in.

 

 

•          Slicing

 

Example :

Str1= “PYTHON STRING”

>>> Str1="PYTHON STRING"

>>> Str1[1:10]

'YTHON STR'

>>> Str1[::]

'PYTHON STRING'

>>> Str1[0:13:2]

'PTO TIG'

>>> Str1[-1:13:2]

'G'

>>> Str1[::-1]

'GNIRTS NOHTYP'

>>> Str1[2:-13:-1]

'TY'

>>> Str1[-2:-13:-1]

'NIRTS NOHTY'

>>> Str1="PYTHON"

>>> Str1[::2]

'PTO'

>>> Str1[:]

'PYTHON'

>>> Str1[-2:]

'ON'

>>> Str1[:-2]

'PYTH'

•   Updating:

Syntax :

          String[range]+ ‘x’

Where  range[start, stop, step]

>>> Str1="PYTHON STRING"

>>> Str1[0:7]+'JYTHON'

'PYTHON JYTHON'

>>> Str1="PYTHON STRING"

>>> "LIST"+Str1[0:7]

'LISTPYTHON '

•   Concatenation: The “+” operator joins or concatenates strings written on both sides of the operator and creates a new string.

Example :

>>> "Welcome "+"Python"

'Welcome Python'

>>> s="Language "+"Python"

>>> print(s)

Language Python

• Replicating/ Repetition: The * operator creates a new string by replicating multiple copies of the same string

Example:

>>> S="Python"

>>> S*3

'PythonPythonPython'

>>> "Jython "*4

'Jython Jython Jython Jython '

•          Membership Operators: 

• in: Returns True if a character or substring exists in the given string, False otherwise
• not in: Returns True if a character or substring does not exist in the given string, False otherwise

Example:

>>> s="Language Python"

>>> 'l' in s

False

>>> 'l' not in s

True

>>> 'P' in "International"

False

>>> 't' in "International"

True

>>> 't' not in "International"

False

>>> 'm' not in "International"

True