Skip to content

README.md

Latest commit

 

History

History
231 lines (181 loc) · 6.1 KB

README.md

File metadata and controls

231 lines (181 loc) · 6.1 KB
Raw

Module 006: Operators (Arithmetic, Comparison, Logical, Assignment)

Phase: 1. Fundamentals | Estimated time: 2 hours | Milestone Project: No

Prerequisites

Learning Objectives

By the end of this module, you will be able to:

  • Use all arithmetic operators including //, %, and **
  • Compare values using ==, !=, <, >, <=, >=
  • Combine conditions with and, or, not
  • Use augmented assignment operators like +=, -=
  • Predict evaluation order using operator precedence

Why This Matters

Operators are the tools you use to compute, compare, and control. Every program — from a simple calculator to a complex AI model — relies on these fundamental operations. Mastering them gives you the vocabulary to express any computation.

Concept Explanation

Arithmetic Operators

Operator Name Example Result
+ Addition 5 + 3 8
- Subtraction 5 - 3 2
* Multiplication 5 * 3 15
/ Division (float) 5 / 3 1.666...
// Floor division 5 // 3 1
% Modulo (remainder) 5 % 3 2
** Exponentiation 5 ** 3 125

Floor Division (//)

Divides and rounds DOWN to the nearest integer:

print(10 // 3)    # 3
print(-10 // 3)   # -4 (rounds DOWN, not toward zero)
print(10.0 // 3)  # 3.0 (float if any operand is float)

Modulo (%)

Returns the remainder after division. Useful for checking even/odd:

print(10 % 3)     # 1
print(15 % 5)     # 0 (divisible)
print(7 % 2)      # 1 (odd)
print(8 % 2)      # 0 (even)

Exponentiation (**)

Raises a number to a power:

print(2 ** 3)      # 8
print(4 ** 0.5)    # 2.0 (square root)
print(10 ** -1)    # 0.1

Comparison Operators

Comparison operators return True or False (boolean):

x = 10
y = 5

print(x == y)    # False (equal to)
print(x != y)    # True (not equal to)
print(x < y)     # False
print(x > y)     # True
print(x <= 10)   # True
print(x >= 10)   # True

You can chain comparisons:

age = 25
print(18 <= age < 65)  # True (age is between 18 and 64 inclusive)

Logical Operators

and, or, not combine boolean values:

age = 20
has_id = True

print(age >= 18 and has_id)   # True (both conditions True)
print(age >= 18 or has_id)    # True (at least one is True)
print(not has_id)             # False (negates)

Truth table for and:

True  and True   → True
True  and False  → False
False and True   → False
False and False  → False

Truth table for or:

True  or True    → True
True  or False   → True
False or True    → True
False or False   → False

Assignment Operators

Beyond simple =, Python provides augmented assignment operators:

Operator Example Equivalent to
+= x += 3 x = x + 3
-= x -= 3 x = x - 3
*= x *= 3 x = x * 3
/= x /= 3 x = x / 3
//= x //= 3 x = x // 3
%= x %= 3 x = x % 3
**= x **= 3 x = x ** 3 
count = 10
count += 5    # count is now 15
count -= 3    # count is now 12
count *= 2    # count is now 24
print(count)

Operator Precedence

Python follows the standard PEMDAS order. From highest to lowest precedence:

  1. ** (exponentiation)
  2. +x, -x (unary plus/minus)
  3. *, /, //, % (multiplication, division)
  4. +, - (addition, subtraction)
  5. ==, !=, <, >, <=, >= (comparison)
  6. not (logical NOT)
  7. and (logical AND)
  8. or (logical OR)
result = 5 + 3 * 2 ** 3
# 2 ** 3 → 8
# 3 * 8 → 24
# 5 + 24 → 29
print(result)  # 29

Use parentheses to make precedence explicit:

result = (5 + 3) * 2 ** 3  # 8 * 8 → 64
print(result)  # 64

Common Pitfalls

  1. / vs //: 10 / 3 is 3.333..., 10 // 3 is 3. Know the difference.
  2. == vs =: if x = 5 is an assignment, not a comparison. Use == for equality checks.
  3. Chaining and/or without parentheses: age > 18 and has_id or is_vip may not mean what you think. Use parentheses: (age > 18 and has_id) or is_vip.
  4. Forgetting that % with negative numbers can surprise you: -5 % 3 gives 1, not -2.
  5. Integer division with negatives: -10 // 3 gives -4 (floor division rounds down).

Hands-On Walkthrough

Let's build a "Number Analyzer" program:

# Get a number from the user
num = int(input("Enter an integer: "))

# Arithmetic
print("Square:", num ** 2)
print("Cube:", num ** 3)
print("Square root (approx):", num ** 0.5)

# Even or odd?
print("Is even?", num % 2 == 0)

# Analysis
print("Positive?", num > 0)
print("Negative?", num < 0)
print("Zero?", num == 0)

# Range check
print("Between 1 and 100?", 1 <= num <= 100)

# Augmented assignment demo
total = 0
total += num
total += 10
print("Total after adding num and 10:", total)

Example run with input 7:

Square: 49
Cube: 343
Square root (approx): 2.6457513110645907
Is even? False
Positive? True
Negative? False
Zero? False
Between 1 and 100? True
Total after adding num and 10: 17

Key Takeaways

  • Arithmetic: +, -, *, /, // (floor), % (modulo), ** (power).
  • Comparison: ==, !=, <, >, <=, >= — all return bool.
  • Logical: and (both True), or (at least one True), not (negation).
  • Augmented assignment: +=, -=, *=, /=, //=, %=, **=.
  • Operator precedence: ** > unary > *//////% > +/- > comparison > not > and > or.
  • Use parentheses to clarify precedence.
  • // rounds down (floor), not toward zero.
  • % gives remainder; x % 2 == 0 checks for even numbers.

Further Reading

Next Module

Dive deeper into text manipulation in Module 007: Strings Deep Dive.