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Ameen Abozaid
Englishالعربية
BEG-010

Operators

  • 6 Lessons
  • 72 min of reading
  • 3 h practice (estimate)
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On this page 8 topics

Overview

Topics

  • Arithmetic
  • comparison
  • logical
  • assignment
  • precedence
  • increment/decrement

Learn first

72 min of reading · 3 h of practice (estimate)

Learning outcomes

  1. Evaluate expressions using arithmetic, comparison, logical, and assignment operators.
  2. Predict results involving integer division, modulo, and operator precedence.
  3. Explain the difference between prefix and postfix increment.
  4. Use short-circuit evaluation (&&, ||) to avoid errors.

Lessons

  1. 01Arithmetic operators and integer division12 min read
  2. 02Comparison and logical operators12 min read
  3. 03Assignment and compound assignment12 min read
  4. 04Increment, decrement, and precedence13 min read
  5. 05Short-circuit evaluation12 min read
  6. 06Demo: predict-then-run expression challenge11 min read

Lab and exercises

Lab

BEG-010-LAB1 · Expression predictor

Outcomes: 1–4 · Time: ~3 h Predict the output of the 20 expressions below on paper, then run them in code. Record each prediction before running and explain each mismatch.

  1. 7 / 2 2. 7 % 2 3. -7 / 2 4. 7 / 2.0 5. 10 % 3 + 1 6. 2 + 3 * 4 7. (2 + 3) * 4 8. 5 > 3 9. 5 == 5.0 10. !(3 > 5)
  2. true && false 12. true || false && false 13. int x = 5; x += 3; (x) 14. int x = 5; x *= 2 + 1; (x) 15. int i = 3; i++; (i)
  3. int i = 3; int j = i++; (i, j) 17. int i = 3; int j = ++i; (i, j) 18. int d = 0; d != 0 && 10 / d > 1 19. 1 + 2 + "3" 20. "1" + 2 + 3

Acceptance: predictions recorded before running; each mismatch explained.

Exercises (assessment: six)

IDOutcomeTask
BEG-010-EX011Write an expression that is true when n is even.
BEG-010-EX021Write an expression for "year is a leap year": divisible by 4 and (not by 100 or divisible by 400).
BEG-010-EX032Compute the average of the ints 7 and 8 as a decimal; first get it wrong, then fix it.
BEG-010-EX042Convert 135 minutes into hours and remaining minutes using / and %.
BEG-010-EX053Predict the final values of a and b: int a = 2; int b = a++ + ++a;
BEG-010-EX064Rewrite 10 / d > 1 && d != 0 so it can never divide by zero.
Show solutions
  • Lab: 1: 3 · 2: 1 · 3: -3 · 4: 3.5 · 5: 2 · 6: 14 · 7: 20 · 8: true · 9: true · 10: true · 11: false · 12: true · 13: 8 · 14: 15 · 15: 4 · 16: i=4, j=3 · 17: i=4, j=4 · 18: false (no crash) · 19: 33 · 20: 123.
  • EX01 n % 2 == 0.
  • EX02 (y % 4 == 0) && (y % 100 != 0 || y % 400 == 0).
  • EX03 (7 + 8) / 2 gives 7; fix: (7 + 8) / 2.0 gives 7.5.
  • EX04 135 / 60 is 2 hours; 135 % 60 is 15 minutes.
  • EX05 a++ yields 2 (a becomes 3); ++a makes a 4 and yields 4; b is 6, a is 4.
  • EX06 d != 0 && 10 / d > 1.

Quiz

Outcomes: O1 evaluate · O2 division, modulo, precedence · O3 prefix/postfix · O4 short-circuit.

A self-check for you: nothing is graded, saved or sent anywhere. Choose an answer, then check it. You can try again as often as you like.

  1. 15 == 5 is:O1
  2. 2x += 2 means:O1
  3. 3true && false is:O1
  4. 49 / 2 is:O2
  5. 59 % 4 is:O2
  6. 62 + 3 * 2 is:O2
  7. 7int i = 1; int j = i++; leaves:O3
  8. 8int i = 1; int j = ++i; leaves:O3
  9. 9In a && b, if a is false then:O4
  10. 10The valid way to write "x between 1 and 10" is:O1

Practical part

Six exercises BEG-010-EX01 to EX06. Pass: at least five correct, and all lab mismatches explained.

Common mistakes

= vs ==; 5/2 returning 2; chaining comparisons like 1 < x < 10.

Assessment

6 exercises.

Career relevance

Exact reasoning about expressions underpins debugging (BEG-018) and test boundaries (BEG-045).

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