Lecture Notes: Introduction to Variables in Programming

Overview

• Fundamental concept in programming: Variables
• Examples given using Python

Key Concepts

What is a Variable?

• Definition: A variable stores information in a program for later use.
• Components:
  • Name: Identifier for the variable.
  • Type: Defines the kind of data stored.
  • Value: The data stored in the variable.

Examples

1. Variable: greeting

   • Type: str (string)
   • Value: "Hello World"
   • Usage: Printing greeting outputs "Hello World" without quotes.

2. Variable: my_number

   • Type: int (integer)
   • Value: 50

Variable Types

String (str)

• Contains text or a sequence of characters.
• Can include letters, numbers, punctuation, and spaces.
• Examples: "Hello World", "abc123", or even an empty string.
• Convention in Python:
  • Double quotes preferred for the course.

Integer (int)

• Contains a whole number (positive, negative, or zero).
• Cannot have decimals.
• Examples: -50, 0, 5

Floating-point Number (float)

• Like an integer but can include decimals.
• Examples: -3.2, 0.0, 4.5652
• Zero point zero (0.0) is equal to integer zero.

Assignment Statements

• Used to create or update variables.
• Structure:
  • Left: Variable Name
  • Middle: Single Equal Sign (=)
  • Right: Value to assign

Using the type Function

• Prints the type of a variable.
• Example: type(greeting) outputs class 'str'.
• For my_number, the output is class 'int'.

Conclusion

• Basics of variables in Python covered.
• Future topics: Advanced operations with variables.