Variables in Python

Introduction

• Variables act like containers in programming.
• Similar to kitchen containers used to store different types of food items, variables store data in programming.
• In Python, variables allow us to store different types of data in memory (RAM).

Data Types

Example of using variables in Python:

A = 1
print(A)  # Outputs: 1

• This stores 1 in memory and assigns the address to A.
• The variable A can now be used to refer to the value 1.

Changing Variable Values

• We can change the value a variable holds.

A = 1
A = 2  # A now holds the value 2

String Variables

B = "Hello"
print(B)  # Outputs: Hello

• Using double quotes to define string data.

Data Type Importance

• Variable data types in Python include:
  • Integers (e.g., A = 1)
  • Strings (e.g., B = "Hello")
  • Floats (e.g., C = 1.1)
  • Complex numbers (e.g., D = 4 + 3j)
  • Booleans (e.g., True or False)
  • Lists and Tuples
  • Dictionaries
• Data type is essential for performing operations on variables.
• Mismatched data types (e.g., adding a string to an integer) will cause errors.

Built-in Data Types in Python

Numeric Types

• Integer: Whole numbers (Example: 1, 2)
• Float: Decimal numbers (Example: 1.1, 3.14)
• Complex: Numbers with real and imaginary parts (Example: 4 + 3j)

String

• Text data enclosed in quotes.

text = "Hello World"

Boolean

• Represents True or False

can_drive = True

Lists

• Ordered collection of elements which can be of different data types.

my_list = [1, "Hello", 3.14]

• Mutable, meaning their content can be changed.

Tuples

• Ordered collection similar to lists but immutable (cannot change elements once defined).

my_tuple = (1, "Hello", 3.14)

Dictionaries

• Collection of key-value pairs.

my_dict = {"name": "Sakshi", "age": 28}

• Allows quick look-ups of elements based on keys.

Notes on Mutability

• Mutable: Objects that can be changed. Example: Lists.
• Immutable: Objects that cannot be changed. Example: Tuples.
• Mutability helps in distinguishing the behavior and usage of different data structures.

Everything is an Object

• In Python, everything is treated as an object. This includes basic data types like integers, strings as well as more complex data types.

Example Code

# Variable and Type Examples
A = 1
B = "Harry"
print(A)  # 1
print(B)  # Harry
print(type(A))  # <class 'int'>
print(type(B))  # <class 'str'>

Conclusion

• Variables are foundational in Python programming, allowing us to store and manipulate different kinds of data effectively.
• Understanding variable types and mutability is crucial for writing efficient and error-free code.