Python Course - Section 4: Syntax & Data Types

Study Notes

Syntax: The rules and structures for writing Python code. Python uses indentation instead of curly braces to define code blocks.
Python Indentation: The spaces at the start of a line are crucial. It tells Python which statements belong together in a block of code.
Indentation Usage: Indentation is used for defining functions, loops, conditional statements, and classes.
Syntax Errors vs. Semantic Errors:
- Syntax Errors: Structural errors in the code (like missing parenthesis). These errors prevent the code from running.
- Semantic Errors: Problems with the meaning or intent of the code. The code might run but produce incorrect results. An example is using the wrong mathematical operator.

Data Types: Categorization of data items. Python uses dynamic typing (a variable's type is determined at runtime).
Data Type Summary:
- Text (String): A sequence of characters (e.g., "hello").
- Numeric: Numbers. Includes:
  - Integer (Int): Whole numbers (e.g., 5, -10).
  - Floating point (Float): Numbers with decimal points (e.g., 3.14, -2.5).
  - Complex: Numbers with real and imaginary parts (e.g., 3 + 5j).
- Boolean (Bool): True or False.
- NoneType: Represents the absence of a value.
- Sequence: An ordered collection of items. Includes:
  - List: Ordered and mutable (changeable).
  - Tuple: Ordered and immutable (not changeable).
  - Range: A sequence of numbers.

Variables: Containers for data values. In Python, you don't need to declare a variable type; it's determined dynamically.
Creating Variables: A variable is created when you assign a value to it.
Variable Declaration: Python has no explicit declaration.

Variable Names: Names of variables follow specific rules.
- Can use letters, numbers, and underscores, but must start with a letter or underscore
- Python keywords (reserved words like if, for, while) cannot be used as variable names.
- Variable names are case-sensitive (e.g. myVariable is different from myvariable).