Python Variable

What are Variables?

A variable in Python acts as a container for storing data. It is a name given to a memory location where data is stored. The Variables make it easier to manage and manipulate data in a program.

Key Features of Python Variables:

• Dynamic Typing: Python variables do not need explicit declaration; their type is determined automatically based on the value assigned.
• Case-Sensitive: The Variable names are case-sensitive (e.g., Age and age are different).
• No Type Declaration: Unlike some other programming languages, Python does not require the declaration of the type of variable.

How to Declare a Variable in Python

In Python, declaring a variable is as simple as assigning the value using the = operator:

# Example of variable assignment 

name = "Alice" # String 

age = 25 # Integer 

is_student = True # Boolean

In the above example:

• name is assigned a string value "Alice".
• age is assigned an integer value 25.
• is_student is assigned a boolean value True.

Rules for Naming Variables

To ensure that your code is readable and avoids errors follow these naming rules:

1) Start with a Letter or Underscore: A variable name must begin with the letter (a-z, A-Z) or an underscore (_).

• Valid: my_var, _temp
• Invalid: 1variable, -name

2) No Spaces: Use underscores (_) to separate words.

• Example: my_variable_name

3) Avoid Reserved Keywords: Python’s reserved keywords (like if, else, while etc.) cannot be used as variable names.

• Invalid: for = 10

4) Case Sensitivity: The Variable names are case-sensitive.

• Example: myVar and myvar are different.

Variable Types in Python

Python supports multiple data types and variables can hold any of these types. The Common types include:

• Integer (int): Whole numbers.

          x = 10

• Floating Point (float): Decimal numbers.

          pi = 3.14

• String (str): Text values.

          greeting = "Hello, World!"

• Boolean (bool): True or False values.

          is_ready = True

• List: Ordered, mutable collections.

          fruits = ["apple", "banana", "cherry"]

• Tuple: Ordered, immutable collections.

          coordinates = (10, 20)

• Dictionary (dict): Key-value pairs.

          person = {"name": "Alice", "age": 25}