Python Tutorial : Variable

 Python Tutorial : Variable 

Python is one of the very popular programming language , it is beginner-friendly as well as professional-friendly and easy to understand .The first concepts every learner must understand is the variable.

A variable is identified by name , variable store value in memory. In Python , variables store data , this data can be used or can be manipulated later. Python does not require to declare a variable type explicitly before assignment , it can be declared and assign dynamically.

Here is the example of variable
x = 10
y = "Hello World"

A variable is a musk like a container that holds data. If we write x = 5
python  creates an object with the value 5 and a reference x that points to this object , then
x is not the value , x is a name pointing to the memory location stored location.

 Data Types of Variables

int

--> Integer (full number or number with point) ,

x = 5

float-->

Decimal number(number with point)

, pi = 3.14

str-->

String (text) ,name = "Hellow World"

 bool-->Boolean (True/False) , isHealthy=true

list-->Ordered,collection ,colors = ["red", "blue", "green"]

tuple-->Ordered, unchangeable collection,point = (10, 20)

dict-->Dictionary Objects ,Key-value pairs,student = {"name": "Ayan", "age": 22}

Example:

name = "Ayan"              --string

_age = 25                       --int

user_name1 = "admin"  --string

isHealthy=true               --boolean

my_dict =                      --dictionaly

{

  "brand": "TATA",

  "model": "KIA",

  "year": 2024

}

class A: pass       

class B: pass

class C: pass

lst = [A, B, C]                --list

How to assign values to variables

Single assignment

Integer variables

age = 25

year = 2025

Float variables

pi = 3.14159

height = 5.8

temperature = -2.5

String variables

name = "Ayan Banerjee"

college = 'Netaji Subhash Engineering College'

course = "M.Tech in CSE"

Boolean variables

is_student = True

is_graduated = False

has_passed = True

List variables

colors = ["red", "green", "blue"]

numbers = [10, 20, 30, 40]

mixed = [1, "Ayan", True, 3.14]

Dictionary

student = {

    "name": "Ayan",

    "age": 25,

    "course": "M.Tech CSE",

    "is_active": True

}

Multiple Assignment in Python

Integer

a, b, c = 10, 20, 30

Float

p, q, r = 3.14, 2.71, 1.61

String

first_name, middle_name, last_name = "Ayan", "Kumar", "Banerjee"

Boolean

is_student, is_active, has_passed = True, True, False

List

colors, numbers, fruits = ["red", "green", "blue"], [1, 2, 3], ["apple", "banana"]

Dictionary

student1, student2, student3 = \

    {"name": "Ayan", "age": 25}, \

    {"name": "Riya", "age": 22}, \

    {"name": "Arjun", "age": 23}

Dynamic Typing in Python

Python has a good feature of Dynamic Typing , than means , you do not do not need to declare the type of a variable explicitly,assign value directly , python will detect automatically variable type .Variable type can be change automatically during execution,which means , variable a is integer can be change to string by assign only

How python assign variable type automatically ?

x = 10             

x = "Hello World"  

How python change variable type ?

Float to Bool

y = 3.14      # float

print(y, type(y))

y = True      # bool

print(y, type(y))

String to List

name = "Python"

print(name, type(name))

name = ["P", "y", "t", "h", "o", "n"]

print(name, type(name))

Boolean to String

flag = False

print(flag, type(flag))

flag = "False"

print(flag, type(flag))

What is the advantage of Dynamic Typing ?

1. No need to declare types manually , development is fast.
2. Variables can change any type of data during runtime.
3. Clean and simple.

Deleting Variables

Deleting Variables in a smart feature of python , deleting is simple and it help free memory in long-running programs.

Delete a single variable

x = 10

del x

Delete multiple variables

a = 5

b = 10

c = 15

del a, b, c

Prepared By : Ayan Banerjee