Variables and Data Types in Python

Variables in Python

  • Variables are used to store data that can be referenced and manipulated in the program.
  • A variable is given to a memory location where data is stored.
  • Python is a dynamically-typed language, which means that you don’t need to declare the type of a variable explicitly. Python determines the type based on the value assigned to the variable.


Example 1: Check variable type

name = "Alice"
age = 25
is_valid = True

print(type(name))
print(type(age))
print(type(is_valid))Code language: PHP (php)
  • Output:
<class 'str'>
<class 'int'>
<class 'bool'>Code language: HTML, XML (xml)


Example 2: Check the memory address of a variable

x = 100
print(id(x))Code language: PHP (php)
  • Output:
140734924203544


Rules for Naming Variables

  1. A variable name must start with a letter (a-z, A-Z) or an underscore (_).
  2. It can contain letters, digits (0-9), and underscores, but cannot start with a digit.
  3. Variable names are case-sensitive (age and Age are different).


Data Types in Python

We will discuss the main categories of Data types in Python:

I- Numeric Types

  • Integer (int): numbers, positive or negative.

Example:

age = 30
print(age)
print(type(age))Code language: PHP (php)

Output:

30
<class 'int'>Code language: HTML, XML (xml)


  • Float: Numbers with decimals

Example:

price = 19.99
print(price)
print(type(price))Code language: PHP (php)

Output:

19.99
<class 'float'>Code language: HTML, XML (xml)


  • Complex: Numbers: Number with real and imaginary numbers

Example:

z = 2 + 3j
print(z)
print(type(z))Code language: PHP (php)

Output:

(2+3j)
<class 'complex'>Code language: HTML, XML (xml)


II- String

str: Sequence of characters enclosed in quotes:

Example:

LD= "Hello! This DearnDuty.com"
print(LD)
print(type(LD))Code language: PHP (php)

Output:

Hello! This DearnDuty.com
<class 'str'>Code language: HTML, XML (xml)


III- Boolean Type

It include a True or False value

Example:

is_active = True
print(is_active)
print(type(is_active))Code language: PHP (php)

Output:

True
<class 'bool'>Code language: PHP (php)


IV- Sequence Types

  • List: a list is an ordered, mutable (modifiable) collection of items.

Example:

fruits = ["apple", "banana", "cherry"]
print(fruits)
print(type(fruits))Code language: PHP (php)

Output:

['apple', 'banana', 'cherry']
<class 'list'>Code language: JavaScript (javascript)


  • Tuple: Ordered, immutable collection of items

Example:

coordinates = (10, 20)
print(coordinates)
print(type(coordinates))Code language: PHP (php)


Output:

(10, 20)
<class 'tuple'>Code language: HTML, XML (xml)


  • Set: Unordered collection of unique items.

Example:

unique_numbers = {1, 2, 3, 4, 5}
print(unique_numbers)
print(type(unique_numbers))Code language: PHP (php)

Output:

{1, 2, 3, 4, 5}
<class 'set'>Code language: HTML, XML (xml)


V- Dictionary

Unordered collection of key-value pairs.

Example:

person = {"name": "Bil", "age": 30}
print(unique_numbers)
print(type(unique_numbers))Code language: PHP (php)

Output:

{1, 2, 3, 4, 5}
<class 'set'>Code language: HTML, XML (xml)


VI- None

Indicate the absence of a value.

value = None


Examples of Variable Assignments and Operations

Single and multiple assignement

  • Single assignement:
x = 5
  • Multiple assignement:

Example:

# Multiple assignments
a, b, c = 10, 20, 30

# Assign the same value to multiple variables
m = n = 0

print(a, b , c)
print(m)
print(n)Code language: PHP (php)

Output:

10 20 30
0
0


Using Variables in Expressions python

num1 = 10
num2 = 20
result = num1 + num2
print(result)Code language: PHP (php)

output

30


Convert Data type

Example:

y = float(result)
print(y)
print(type(y))Code language: PHP (php)


Output:

30.0
<class 'float'>Code language: HTML, XML (xml)


Check the

Bilel Ameur

Enthusiastic Network Engineer specializing in Cisco ACI, passionate about solving challenges. A lifelong learner who loves gaining and sharing knowledge. Profile: https://www.linkedin.com/in/bilel-ameur-71116b2b5
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