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App Dev Worksheet: Debugging

App development lesson 21: Debugging: find the bug line · Set 892 · 40 questions
TalentJR

Developer's tip (Compare with the comment): Read each line and its comment (after //): does the code do exactly that? Actual = run the lines as written. Expected = follow every comment. After the fix, test again.

NameDateTime takenScore ___ / 40
  1. 1.🐞 What is a bug? (a) a nice icon (b) a fast phone (c) a mistake in the code (d) a new feature
  2. 2.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let score = 39; // start at 39
    line 2: score = score + 3; // take away 3
    line 3: score = score + 2; // add 2
    line 4: show(score); // show it     (a) line 2 (b) line 1 (c) line 3
  3. 3.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 42; // start at 42
    line 2: lives = lives - 1; // take away 1
    line 3: lives = lives - 6; // add 6
    line 4: show(lives); // show it
  4. 4.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let points = 48; // start at 48
    line 2: points = points * 2; // double it
    line 3: points = points + 4; // take away 4
    line 4: points = points * 2; // double it
    line 5: show(points); // show it
  5. 5.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let points = 39; // start at 39
    line 2: points = points - 6; // add 6
    line 3: points = points - 3; // take away 3
    line 4: points = points * 2; // double it
    line 5: show(points); // show it
  6. 6.🐞 Finding and fixing bugs is called ___. (a) debugging (b) decorating (c) designing (d) downloading
  7. 7.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 34; // start at 34
    line 2: score = score + 4; // add 4
    line 3: score = score + 1; // take away 1
    line 4: show(score); // show it
  8. 8.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 35; // start at 34
    line 2: score = score - 4; // take away 4
    line 3: score = score - 3; // take away 3
    line 4: show(score); // show it
  9. 9.🐞 What is a good first step when an app gives a wrong result? (a) buy a new phone (b) delete the app (c) add more colours (d) find where it goes wrong
  10. 10.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 48; // start at 48
    line 2: stars = stars + 5; // add 5
    line 3: stars = stars + 5; // add 2
    line 4: stars = stars + 2; // add 2
    line 5: show(stars); // show it
  11. 11.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 36; // start at 36
    line 2: score = score + 2; // add 2
    line 3: score = score + 2; // add 2
    line 4: score = score + 2; // double it
    line 5: show(score); // show it
  12. 12.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let lives = 41; // start at 39
    line 2: lives = lives + 6; // add 6
    line 3: lives = lives * 2; // double it
    line 4: show(lives); // show it
  13. 13.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let points = 45; // start at 45
    line 2: points = points * 2; // double it
    line 3: points = points + 2; // double it
    line 4: points = points * 2; // double it
    line 5: show(points); // show it
  14. 14.🐞 After fixing a bug you should ___. (a) never test (b) delete the test (c) test it again (d) release at once
  15. 15.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let points = 44; // start at 44
    line 2: points = points + 2; // double it
    line 3: points = points + 4; // add 4
    line 4: points = points * 2; // double it
    line 5: show(points); // show it
  16. 16.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let coins = 50; // start at 50
    line 2: coins = coins * 2; // double it
    line 3: coins = coins - 1; // take away 1
    line 4: coins = coins + 7; // add 6
    line 5: show(coins); // show it
  17. 17.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let coins = 47; // start at 47
    line 2: coins = coins - 6; // take away 5
    line 3: coins = coins * 2; // double it
    line 4: show(coins); // show it     (a) line 3 (b) line 1 (c) line 2
  18. 18.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 39; // start at 37
    line 2: score = score + 4; // add 4
    line 3: score = score - 3; // take away 3
    line 4: show(score); // show it
  19. 19.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let coins = 40; // start at 40
    line 2: coins = coins * 2; // double it
    line 3: coins = coins + 4; // add 2
    line 4: coins = coins * 2; // double it
    line 5: show(coins); // show it     (a) line 1 (b) line 4 (c) line 2 (d) line 3
  20. 20.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 50; // start at 50
    line 2: score = score - 3; // take away 2
    line 3: score = score + 2; // add 2
    line 4: show(score); // show it
  21. 21.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 52; // start at 49
    line 2: lives = lives - 1; // take away 1
    line 3: lives = lives * 2; // double it
    line 4: show(lives); // show it
  22. 22.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let points = 40; // start at 38
    line 2: points = points + 6; // add 6
    line 3: points = points * 2; // double it
    line 4: show(points); // show it
  23. 23.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let coins = 31; // start at 30
    line 2: coins = coins + 5; // add 5
    line 3: coins = coins + 6; // add 6
    line 4: coins = coins + 6; // add 6
    line 5: show(coins); // show it
  24. 24.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 47; // start at 47
    line 2: stars = stars + 6; // add 6
    line 3: stars = stars * 3; // double it
    line 4: show(stars); // show it
  25. 25.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 36; // start at 36
    line 2: score = score + 6; // add 6
    line 3: score = score - 1; // take away 1
    line 4: score = score - 5; // add 5
    line 5: show(score); // show it
  26. 26.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let coins = 35; // start at 35
    line 2: coins = coins - 2; // take away 2
    line 3: coins = coins - 3; // take away 1
    line 4: coins = coins + 6; // add 6
    line 5: show(coins); // show it
  27. 27.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let lives = 42; // start at 40
    line 2: lives = lives * 2; // double it
    line 3: lives = lives - 4; // take away 4
    line 4: show(lives); // show it     (a) line 2 (b) line 1 (c) line 3
  28. 28.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let points = 42; // start at 41
    line 2: points = points + 5; // add 5
    line 3: points = points * 2; // double it
    line 4: show(points); // show it
  29. 29.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let stars = 34; // start at 34
    line 2: stars = stars + 7; // add 6
    line 3: stars = stars + 6; // add 6
    line 4: show(stars); // show it     (a) line 3 (b) line 1 (c) line 2
  30. 30.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let coins = 45; // start at 45
    line 2: coins = coins - 3; // add 3
    line 3: coins = coins - 4; // take away 4
    line 4: coins = coins * 2; // double it
    line 5: show(coins); // show it
  31. 31.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 44; // start at 41
    line 2: lives = lives - 2; // take away 2
    line 3: lives = lives - 4; // take away 4
    line 4: show(lives); // show it
  32. 32.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 46; // start at 45
    line 2: score = score - 1; // take away 1
    line 3: score = score + 5; // add 5
    line 4: show(score); // show it
  33. 33.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 50; // start at 50
    line 2: lives = lives + 3; // add 3
    line 3: lives = lives + 6; // add 6
    line 4: lives = lives - 5; // add 5
    line 5: show(lives); // show it
  34. 34.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let stars = 42; // start at 42
    line 2: stars = stars * 2; // double it
    line 3: stars = stars + 4; // take away 4
    line 4: show(stars); // show it
  35. 35.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let points = 40; // start at 40
    line 2: points = points + 6; // add 6
    line 3: points = points + 2; // double it
    line 4: points = points - 1; // take away 1
    line 5: show(points); // show it     (a) line 4 (b) line 3 (c) line 2 (d) line 1
  36. 36.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let coins = 48; // start at 48
    line 2: coins = coins - 5; // take away 4
    line 3: coins = coins + 6; // add 6
    line 4: show(coins); // show it     (a) line 3 (b) line 2 (c) line 1
  37. 37.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let lives = 31; // start at 31
    line 2: lives = lives + 2; // double it
    line 3: lives = lives + 3; // add 3
    line 4: show(lives); // show it
  38. 38.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let lives = 39; // start at 36
    line 2: lives = lives - 1; // take away 1
    line 3: lives = lives * 2; // double it
    line 4: show(lives); // show it     (a) line 2 (b) line 3 (c) line 1
  39. 39.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let score = 33; // start at 33
    line 2: score = score + 5; // add 5
    line 3: score = score * 3; // double it
    line 4: score = score - 5; // take away 5
    line 5: show(score); // show it     (a) line 3 (b) line 1 (c) line 4 (d) line 2
  40. 40.🐞 A comment in code (after //) is for ___. (a) the phone screen (b) the app store (c) the battery (d) people reading the code

Answer key

  1. a mistake in the code
  2. line 2
  3. 47
  4. 184
  5. 60
  6. debugging
  7. 37
  8. 28
  9. find where it goes wrong
  10. 60
  11. 80
  12. 94
  13. 360
  14. test it again
  15. 184
  16. 105
  17. line 2
  18. 38
  19. line 3
  20. 50
  21. 96
  22. 92
  23. 47
  24. 159
  25. 36
  26. 36
  27. line 1
  28. 94
  29. line 2
  30. 88
  31. 35
  32. 49
  33. 64
  34. 80
  35. line 3
  36. line 2
  37. 36
  38. line 1
  39. line 3
  40. people reading the code

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