jan-2026-python-week-1-comprehensive-notes

Course: Jan 2026 - Programming in Python Topic: Fundamentals of Computing

1. Variables and Data Types

1.1 Core Types

• int: Whole numbers ($5, -42, 0$).
• float: Floating-point numbers ($3.14, 2.0, -0.001$).
• str: Text sequences enclosed in quotes ("Hello", 'Python').
• bool: Logical values (True, False).

1.2 Type Identification

python
Run Inline
type(10)      # <class 'int'>
type(10.0)    # <class 'float'>
type("10")    # <class 'str'>

2. Arithmetic Operations

2.1 Operators

2.2 Operator Precedence (BEDMAS)

1. Parantheses ()
2. Exponentiation ** (Right-associative: $2**3**2 = 2^{3^2} = 2^9 = 512$)
3. Multiplication/Division *, /, //, % (Left-associative)
4. Addition/Subtraction +, - (Left-associative)

3. String Basics

3.1 Indexing

python
Run Inline
s = "Python"
s[0]  # 'P'
s[-1] # 'n' (negative indexing)

3.2 Slicing [start : stop : step]

• start: Inclusive
• stop: Exclusive
• step: Interval

python
Run Inline
s = "123456"
s[1:4]   # "234"
s[::2]   # "135" (Every 2nd char)
s[::-1]  # "654321" (Reverse)

4. Input and Output

4.1 print()

• Can display any data type (converts to string internally).
• Default end is \n (newline).
• Default sep is " " (space).

4.2 input()

• Always returns a string.
• To get numbers, you must cast it: x = int(input()).

5. Logical Operators & Truthiness

5.1 Operators

• not (Highest precedence)
• and
• or (Lowest precedence)

5.2 Truthiness

• None
• False
• 0 (int), 0.0 (float)
• "" (Empty string)
• [], {}, set() (Empty collections)

6. Abbreviations & Mnemonics

• Please Excuse My Dear Aunt Sally (PEMDAS)
• STU (String index starts at 0): String The zero-Up.