Variables and Data Type

Variables

Rules for Python variables:

• A variable name must start with a letter or the underscore character.

• A variable name cannot start with a number.

• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )

• Variable names are case-sensitive (age, Age, and AGE are three different variables)

Data Type

• int: Integer number type. e.g: age = 25

• float: Floating-point number. e.g: pi= 3.14

• str: Textual data type. e.g: greeting= "Hello Multiverses"

• bool: Boolean true/false. e.g: is_valid = True

• list: Ordered collection mutable. e.g: fruits = ["Apple", "Banana"]

• tuple: Ordered collection immutable. e.g: coordinates = (7, 14)

• dict: Key-value pairs. e.g: person = {"name": "Saim", "age": 20}

• set: Unordered unique elements. e.g: unique_numbers = {1,2,7,14}

Expressions

• Basic Arithmetic Expressions
  Use +, -, *, and / for basic operations.

  result = 5 + 3 * 2 - 1 / 2 # Output: 10.5

• Modulus and Exponentiation
  % returns remainder, ** raises power.

  remainder = 10 % 3 # Output: 1 power = 2 ** 3 # Output: 8

• String Concatenation and Repetition
  Use + to combine strings, and * to repeat.

  greeting = "Hello" + " World" # Output: "Hello World" repeat = "Hi! " * 3 # Output: "Hi! Hi! Hi! "

• Comparison Expressions
  Compare values with ==, !=, <, >, <=, >=.

  is_equal = (5 == 5) # Output: True is_greater = (5 > 3) # Output: True

• Logical Expressions
  Combine expressions with and, or, not.

  condition = (5 > 3) and (3 < 7) # Output: True

• Membership Tests
  Check if an element exists within a container using in or not in.

  exists = "apple" in ["apple", "banana", "cherry"] # Output: True

• Ternary (Conditional) Expressions
  Short-hand if-else statements with a if condition else b.

  • age = 18

  • status = "Adult" if age >= 18 else "Minor" # Output: "Adult"

Conditionals