Chapter 2: Variables and data types

In Python, variables are used to store data. They act as placeholders that allow you to refer to values by a name. Here are the key points about Python variables and data types:

    Variable Assignment:

• To assign a value to a variable, you use the assignment operator (=).
• The variable name should follow the rules of Python naming conventions (e.g., no spaces, start with a letter or underscore, case-sensitive).
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  Variable Naming:

  1. Variable names should be descriptive, meaningful, and follow Python's naming conventions.
  2. They can contain letters, digits, and underscores.
  3. Variable names are case-sensitive.
  
  
  

• Introduction to Data Types: Python supports several built-in data types:

• Numeric types:

  • Integers (int): Whole numbers without a fractional part, e.g., 10, -5, 0.
  • Floating-point numbers (float): Real numbers with a decimal point, e.g., 3.14, -2.5.

• Text type:

  • Strings (str): Ordered sequences of characters enclosed in single or double quotes, e.g., "Hello", 'Python'.

• Boolean type:

  • Booleans (bool): Represents the truth values True or False.

• Sequence types:

  • Lists (list): Ordered, mutable collections of items, enclosed in square brackets [], e.g., [1, 2, 3].
  • Tuples (tuple): Ordered, immutable collections of items, enclosed in parentheses (), e.g., (1, 2, 3).

• Mapping type:

  • Dictionaries (dict): Unordered collections of key-value pairs, enclosed in curly braces {}, e.g., {"name": "John", "age": 25}.

• Other types:

• Sets (set): Unordered collections of unique items, enclosed in curly braces {}, e.g., {1, 2, 3}.
• None: A special type representing the absence of a value.
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• Example:
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• # Numeric types age = 25 price = 9.99 # Text type name = "John Doe" # Boolean type is_student = True # Lists numbers = [1, 2, 3] fruits = ['apple', 'banana', 'orange'] # Tuples coordinates = (10, 20) # Dictionaries person = {'name': 'John', 'age': 30}

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