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Learn Variables in Python

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What is a Variable?

 Variables are fundamental in Python, allowing you to store, manipulate, and retrieve data efficiently. Understanding how to use them effectively is crucial for writing dynamic and functional code. A variable is like a storage box where you can keep data. You can think of it as a named reference to a value that can change. Variables allow you to store information, manipulate it, and reuse it throughout your program. If you'd like to explore specific scenarios or have any questions about variables, I hope below explanation and examples may help you to understand the variables in python.

Basic Syntax

To create a variable, you simply assign a value to it using the equals sign (=).

    For example:
  • name = "Alice"
  • temperature = 22.5
  • age = 30

Key Characteristics of Variables

 1. Naming: Variable names can include letters, numbers, and underscores but cannot start with a number. Names are case-sensitive (age and Age are different).
2. Data Types: Variables can hold different types of data, such as:

  • Integers (int): Whole numbers (e.g., 42)
  • Floats (float): Decimal numbers (e.g., 3.14)
  • Strings (str): Text (e.g., "Hello")
  • Booleans (bool): True or False values.

Examples on variables in python
Example 1: Storing Personal Information

Imagine you are storing information about a person:

name = "John Doe"
age = 28
height = 5.9
# in feetis_student = True

Here, you’re using variables to store the name, age, height, and student status of a person.

Example 2: Calculating Expenses

If you want to track your expenses for a week:

monday_expense = 20.50
tuesday_expense = 15.75
wednesday_expense = 30.00
total_expense = monday_expense + tuesday_expense + wednesday_expense
print("Total weekly expense:", total_expense)

This example shows how variables help you perform calculations and keep track of data.

Example 3: Inventory Management

Consider a simple inventory system for a store:

item_name = "Apples"
item_price = 1.50
item_quantity = 100
total_value = item_price * item_quantity
print(f"Total value of {item_name}: ${total_value}")
Reassigning Variables
You can change the value of a variable at any time:
age = 30
print(age)  # Output: 30
age = 31
print(age)  # Output: 31

Variable Scope

Variables have different scopes, which define where they can be accessed.

There are two main types:

1. Local Variables: Variables defined inside a function. They can only be accessed within that function.
2. Global Variables: Variables defined outside of any function. They can be accessed throughout the entire program.

Example of Scope

def my_function():
local_var = 10  # Local variable
    print(local_var)
my_function()
# print(local_var)  # This would raise an error because local_var is not accessible here.
global_var = 20  # Global variable
def another_function():
    print(global_var)  # This can access global_var
another_function()  # Output: 20