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App Dev Worksheet: Debugging

App development lesson 21: Debugging: find the bug line · Set 388 · 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.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let stars = 30; // start at 30
    line 2: stars = stars + 4; // take away 4
    line 3: stars = stars - 2; // take away 2
    line 4: stars = stars + 6; // add 6
    line 5: show(stars); // show it     (a) line 3 (b) line 4 (c) line 1 (d) line 2
  2. 2.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 40; // start at 40
    line 2: score = score + 3; // take away 3
    line 3: score = score * 2; // double it
    line 4: show(score); // show it
  3. 3.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 38; // start at 38
    line 2: score = score + 1; // take away 1
    line 3: score = score * 2; // double it
    line 4: score = score * 2; // double it
    line 5: show(score); // 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 lives = 34; // start at 34
    line 2: lives = lives - 4; // take away 4
    line 3: lives = lives - 2; // take away 2
    line 4: lives = lives - 4; // add 4
    line 5: show(lives); // show it
  5. 5.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 37; // start at 37
    line 2: lives = lives - 6; // add 6
    line 3: lives = lives - 2; // take away 2
    line 4: show(lives); // show it
  6. 6.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let stars = 44; // start at 44
    line 2: stars = stars + 3; // add 3
    line 3: stars = stars - 3; // add 3
    line 4: stars = stars - 4; // take away 4
    line 5: show(stars); // show it     (a) line 3 (b) line 1 (c) line 2 (d) line 4
  7. 7.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let points = 51; // start at 49
    line 2: points = points * 2; // double it
    line 3: points = points - 3; // take away 3
    line 4: points = points + 4; // add 4
    line 5: show(points); // show it
  8. 8.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let stars = 39; // start at 37
    line 2: stars = stars * 2; // double it
    line 3: stars = stars + 4; // add 4
    line 4: show(stars); // show it     (a) line 1 (b) line 2 (c) line 3
  9. 9.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 41; // start at 41
    line 2: lives = lives * 2; // double it
    line 3: lives = lives + 2; // double it
    line 4: lives = lives * 2; // double it
    line 5: show(lives); // show it
  10. 10.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 34; // start at 34
    line 2: stars = stars * 2; // double it
    line 3: stars = stars - 1; // take away 1
    line 4: stars = stars + 5; // 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 points = 36; // start at 34
    line 2: points = points + 5; // add 5
    line 3: points = points + 2; // add 2
    line 4: points = points * 2; // double it
    line 5: show(points); // show it
  12. 12.🐞 Finding and fixing bugs is called ___. (a) downloading (b) decorating (c) designing (d) debugging
  13. 13.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let lives = 40; // start at 39
    line 2: lives = lives + 6; // add 6
    line 3: lives = lives + 2; // add 2
    line 4: show(lives); // show it     (a) line 2 (b) line 3 (c) line 1
  14. 14.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let lives = 33; // start at 33
    line 2: lives = lives * 2; // double it
    line 3: lives = lives - 2; // take away 2
    line 4: lives = lives * 3; // double it
    line 5: show(lives); // show it
  15. 15.🐞 What is a good first step when an app gives a wrong result? (a) find where it goes wrong (b) delete the app (c) add more colours (d) buy a new phone
  16. 16.🐞 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 43
    line 2: lives = lives * 2; // double it
    line 3: lives = lives * 2; // double it
    line 4: lives = lives + 6; // add 6
    line 5: show(lives); // show it
  17. 17.🐞 After fixing a bug you should ___. (a) test it again (b) never test (c) release at once (d) delete the test
  18. 18.🐞 A comment in code (after //) is for ___. (a) the battery (b) the app store (c) the phone screen (d) people reading the code
  19. 19.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let stars = 33; // start at 31
    line 2: stars = stars + 5; // add 5
    line 3: stars = stars + 6; // add 6
    line 4: stars = stars + 3; // add 3
    line 5: show(stars); // show it
  20. 20.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 38; // start at 38
    line 2: score = score - 1; // take away 1
    line 3: score = score - 6; // add 6
    line 4: score = score - 3; // take away 3
    line 5: 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 score = 43; // start at 43
    line 2: score = score + 7; // add 4
    line 3: score = score - 3; // take away 3
    line 4: show(score); // show it
  22. 22.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let points = 43; // start at 42
    line 2: points = points + 5; // add 5
    line 3: points = points + 5; // add 5
    line 4: points = points + 4; // add 4
    line 5: show(points); // show it
  23. 23.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let coins = 36; // start at 36
    line 2: coins = coins - 1; // take away 1
    line 3: coins = coins - 4; // add 4
    line 4: show(coins); // show it
  24. 24.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let lives = 36; // start at 34
    line 2: lives = lives - 2; // take away 2
    line 3: lives = lives - 3; // take away 3
    line 4: lives = lives - 4; // take away 4
    line 5: show(lives); // show it
  25. 25.🐞 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 - 2; // take away 2
    line 3: score = score - 1; // take away 1
    line 4: show(score); // show it
  26. 26.🐞 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 + 3; // add 3
    line 3: points = points - 3; // add 3
    line 4: show(points); // show it     (a) line 2 (b) line 1 (c) line 3
  27. 27.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 32; // start at 32
    line 2: score = score + 2; // add 2
    line 3: score = score + 8; // add 6
    line 4: show(score); // show it
  28. 28.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let coins = 35; // start at 35
    line 2: coins = coins * 3; // double it
    line 3: coins = coins + 4; // add 4
    line 4: show(coins); // show it
  29. 29.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 32; // start at 32
    line 2: score = score * 3; // double it
    line 3: score = score + 6; // add 6
    line 4: show(score); // show it
  30. 30.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let lives = 39; // start at 37
    line 2: lives = lives + 4; // add 4
    line 3: lives = lives * 2; // double it
    line 4: show(lives); // show it     (a) line 2 (b) line 3 (c) line 1
  31. 31.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 35; // start at 33
    line 2: stars = stars * 2; // double it
    line 3: stars = stars + 4; // add 4
    line 4: show(stars); // show it
  32. 32.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let coins = 36; // start at 36
    line 2: coins = coins * 2; // double it
    line 3: coins = coins - 3; // take away 2
    line 4: show(coins); // show it     (a) line 2 (b) line 3 (c) line 1
  33. 33.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let coins = 44; // start at 44
    line 2: coins = coins * 2; // double it
    line 3: coins = coins * 2; // double it
    line 4: coins = coins + 2; // double it
    line 5: show(coins); // show it     (a) line 1 (b) line 2 (c) line 3 (d) line 4
  34. 34.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 40; // start at 38
    line 2: score = score + 4; // add 4
    line 3: score = score - 2; // take away 2
    line 4: show(score); // show it
  35. 35.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let coins = 39; // start at 38
    line 2: coins = coins + 2; // add 2
    line 3: coins = coins * 2; // double it
    line 4: show(coins); // show it
  36. 36.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 37; // start at 34
    line 2: score = score - 4; // take away 4
    line 3: score = score + 3; // add 3
    line 4: score = score * 2; // double it
    line 5: show(score); // show it
  37. 37.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 32; // start at 32
    line 2: lives = lives + 4; // add 4
    line 3: lives = lives - 3; // take away 2
    line 4: lives = lives * 2; // double it
    line 5: show(lives); // show it
  38. 38.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let lives = 38; // start at 38
    line 2: lives = lives + 2; // add 2
    line 3: lives = lives + 2; // double it
    line 4: show(lives); // show it
  39. 39.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let score = 35; // start at 35
    line 2: score = score + 9; // add 6
    line 3: score = score + 5; // add 5
    line 4: score = score * 2; // double it
    line 5: show(score); // show it     (a) line 1 (b) line 4 (c) line 2 (d) line 3
  40. 40.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 36; // start at 36
    line 2: score = score * 2; // double it
    line 3: score = score - 1; // take away 1
    line 4: score = score * 3; // double it
    line 5: show(score); // show it

Answer key

  1. line 2
  2. 86
  3. 148
  4. 32
  5. 41
  6. line 3
  7. 103
  8. line 1
  9. 328
  10. 72
  11. 82
  12. debugging
  13. line 1
  14. 192
  15. find where it goes wrong
  16. 178
  17. test it again
  18. people reading the code
  19. 45
  20. 28
  21. 44
  22. 56
  23. 31
  24. 27
  25. 34
  26. line 3
  27. 42
  28. 74
  29. 70
  30. line 1
  31. 74
  32. line 3
  33. line 4
  34. 40
  35. 80
  36. 72
  37. 68
  38. 42
  39. line 2
  40. 213

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