Strings - Python

Strings:

^v       Strings

^v       String slices

^v       Immutability

^v       String functions and methods

^v       String module

Strings:

^v       String is defined as sequence of characters represented in quotation marks (either single quotes ( ‘ ) or double quotes ( “ ).

^v       An individual character in a string is accessed using a index.

^v       The index should always be an integer (positive or negative).

^v       A index starts from 0 to n-1.

^v       Strings are immutable i.e. the contents of the string cannot be changed after it is created.

^v       Python will get the input at run time by default as a string.

^v       Python does not support character data type. A string of size 1 can be treated as characters.

1. single quotes ('           ')

2.              double quotes (" ")

3.              triple quotes(“”” “”””)

Operations on string:

1.              Indexing

2.              Slicing

3.              Concatenation

4.              Repetitions

5.              Member ship

String slices:

^v                 A part of a string is called string slices.

^v                 The process of extracting a sub string from a string is called slicing.

Immutability:

^v                 Python strings are “immutable” as they cannot be changed after they are created.

^v                 Therefore [ ] operator cannot be used on the left side of an assignment.

string built in functions and methods:

A method is a function that “belongs to” an object.

Syntax to access the method

Stringname.method()

a=”happy birthday”

here, a is the string name.

String modules:

^v       A module is a file containing Python definitions, functions, statements.

^v       Standard library of Python is extended as modules.

^v       To use these modules in a program, programmer needs to import the module.

^v       Once we import a module, we can reference or use to any of its functions or variables in our code.

^v       There is large number of standard modules also available in python.

^v       Standard modules can be imported the same way as we import our user-defined modules.

Syntax:

import module_name

Example

import string

print(string.punctuation)

print(string.digits)

print(string.printable)

print(string.capwords("happ

y birthday"))

print(string.hexdigits)

print(string.octdigits)

output

!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~

0123456789

0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJ

KLMNOPQRSTUVWXYZ!"#$%&'()*+,-

./:;<=>?@[\]^_`{|}~

Happy Birthday

0123456789abcdefABCDEF

01234567

Escape sequences in string