Python Variables

Python Variables – A Brief Overview

What Are Variables?
Variables store data that can be referenced and manipulated. Python uses dynamic typing, meaning variables don’t need explicit type declarations.

Rules for Naming Variables

• Can contain letters, digits, and underscores (_), but cannot start with a digit.
• Case-sensitive (myVar and myvar are different).
• Cannot use Python keywords (e.g., if, class).

Assigning Values

Basic Assignment:

x = 5
name = "John"

Multiple Assignments:

a, b, c = 1, 2, 3

Same Value to Multiple Variables:

x = y = z = 10

Type Casting

Convert between data types using:

• int(), float(), str()

Example:

n = int("10")
f = float(5)
s = str(25)

Checking Variable Type

Use type(variable) to check data type.

Scope of Variables

Local Variables: Exist inside functions only.

def f():
    a = "I am local"
    print(a)

Global Variables: Accessible throughout the program using global keyword.

a = "I am global"
def f():
    global a
    a = "Modified globally"
    print(a)

Object References

• Variables reference objects, not store them directly.
• Changing a variable’s value creates a new reference.

Deleting Variables

Use del variable_name to remove a variable.

x = 10
del x

Practical Examples

Swapping Variables:

a, b = b, a

Counting Characters in a String:

word = "Python"
length = len(word)
print("Length of the word:", length)

Python Variables – Summary

• Variables store data and are dynamically typed.
• Follow naming rules and use int(), float(), and