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App Dev Worksheet: Debugging

App development lesson 21: Debugging: find the bug line · Set 226 · 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.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let lives = 45; // start at 45
    line 2: lives = lives + 2; // add 2
    line 3: lives = lives + 2; // double it
    line 4: show(lives); // show it
  2. 2.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 42; // start at 42
    line 2: stars = stars * 2; // double it
    line 3: stars = stars + 8; // add 6
    line 4: stars = stars - 5; // take away 5
    line 5: show(stars); // 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 stars = 33; // start at 30
    line 2: stars = stars + 5; // add 5
    line 3: stars = stars - 5; // take away 5
    line 4: show(stars); // show it
  4. 4.🐞 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 + 5; // take away 5
    line 3: stars = stars + 2; // add 2
    line 4: stars = stars + 2; // add 2
    line 5: show(stars); // show it     (a) line 2 (b) line 3 (c) line 4 (d) line 1
  5. 5.🐞 What is a bug? (a) a fast phone (b) a mistake in the code (c) a nice icon (d) a new feature
  6. 6.🐞 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 40
    line 2: lives = lives + 5; // add 5
    line 3: lives = lives + 3; // add 3
    line 4: show(lives); // show it
  7. 7.🐞 Finding and fixing bugs is called ___. (a) decorating (b) downloading (c) designing (d) debugging
  8. 8.🐞 A comment in code (after //) is for ___. (a) people reading the code (b) the battery (c) the phone screen (d) the app store
  9. 9.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let coins = 44; // start at 44
    line 2: coins = coins - 6; // add 6
    line 3: coins = coins + 6; // add 6
    line 4: coins = coins - 2; // take away 2
    line 5: show(coins); // show it
  10. 10.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let score = 43; // start at 43
    line 2: score = score + 4; // take away 4
    line 3: score = score - 5; // take away 5
    line 4: show(score); // show it     (a) line 2 (b) line 1 (c) line 3
  11. 11.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let lives = 43; // start at 40
    line 2: lives = lives - 1; // take away 1
    line 3: lives = lives + 2; // add 2
    line 4: show(lives); // show it     (a) line 2 (b) line 1 (c) line 3
  12. 12.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let score = 35; // start at 35
    line 2: score = score + 6; // add 6
    line 3: score = score + 2; // double it
    line 4: score = score - 2; // take away 2
    line 5: show(score); // show it
  13. 13.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let points = 35; // start at 35
    line 2: points = points + 6; // add 6
    line 3: points = points * 3; // double it
    line 4: points = points + 5; // add 5
    line 5: show(points); // show it     (a) line 4 (b) line 1 (c) line 2 (d) line 3
  14. 14.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let points = 44; // start at 41
    line 2: points = points * 2; // double it
    line 3: points = points + 3; // add 3
    line 4: show(points); // show it
  15. 15.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 47; // start at 46
    line 2: stars = stars * 2; // double it
    line 3: stars = stars + 4; // add 4
    line 4: show(stars); // show it
  16. 16.🐞 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 + 8; // add 6
    line 3: score = score + 2; // add 2
    line 4: score = score * 2; // double it
    line 5: show(score); // show it     (a) line 2 (b) line 3 (c) line 1 (d) line 4
  17. 17.🐞 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 38
    line 2: score = score * 2; // double it
    line 3: score = score + 6; // add 6
    line 4: show(score); // show it
  18. 18.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let points = 39; // start at 36
    line 2: points = points + 3; // add 3
    line 3: points = points - 2; // take away 2
    line 4: show(points); // show it
  19. 19.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let points = 50; // start at 50
    line 2: points = points + 4; // add 3
    line 3: points = points * 2; // double it
    line 4: show(points); // show it     (a) line 1 (b) line 3 (c) line 2
  20. 20.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let lives = 44; // start at 41
    line 2: lives = lives - 2; // take away 2
    line 3: lives = lives + 2; // add 2
    line 4: show(lives); // show it     (a) line 3 (b) line 2 (c) line 1
  21. 21.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 47; // start at 47
    line 2: score = score - 2; // take away 2
    line 3: score = score + 4; // add 4
    line 4: score = score + 2; // double it
    line 5: 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 stars = 31; // start at 31
    line 2: stars = stars - 1; // take away 1
    line 3: stars = stars + 2; // double it
    line 4: stars = stars + 2; // add 2
    line 5: show(stars); // 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 score = 31; // start at 31
    line 2: score = score - 2; // take away 2
    line 3: score = score + 6; // add 6
    line 4: score = score - 6; // add 6
    line 5: show(score); // show it
  24. 24.🐞 After fixing a bug you should ___. (a) delete the test (b) release at once (c) test it again (d) never test
  25. 25.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 42; // start at 42
    line 2: stars = stars + 2; // take away 2
    line 3: stars = stars + 6; // add 6
    line 4: stars = stars - 1; // take away 1
    line 5: show(stars); // show it
  26. 26.🐞 This code has a bug. What number SHOULD it show, if every line did what its comment says?
    line 1: let points = 40; // start at 40
    line 2: points = points * 2; // double it
    line 3: points = points + 5; // take away 5
    line 4: show(points); // show it
  27. 27.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let lives = 40; // start at 37
    line 2: lives = lives * 2; // double it
    line 3: lives = lives - 5; // take away 5
    line 4: show(lives); // show it
  28. 28.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 46; // start at 46
    line 2: stars = stars * 2; // double it
    line 3: stars = stars * 2; // double it
    line 4: stars = stars + 2; // double it
    line 5: show(stars); // 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 lives = 40; // start at 40
    line 2: lives = lives * 2; // double it
    line 3: lives = lives - 4; // take away 1
    line 4: show(lives); // show it
  30. 30.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let stars = 33; // start at 31
    line 2: stars = stars + 6; // add 6
    line 3: stars = stars + 2; // add 2
    line 4: show(stars); // 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 score = 44; // start at 44
    line 2: score = score - 5; // take away 4
    line 3: score = score - 5; // take away 5
    line 4: show(score); // 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 coins = 47; // start at 47
    line 2: coins = coins - 3; // take away 3
    line 3: coins = coins + 7; // add 5
    line 4: show(coins); // 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 points = 32; // start at 32
    line 2: points = points - 3; // take away 3
    line 3: points = points + 7; // add 4
    line 4: show(points); // show it
  34. 34.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 44; // start at 44
    line 2: score = score - 1; // take away 1
    line 3: score = score * 3; // double it
    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 score = 35; // start at 34
    line 2: score = score + 6; // add 6
    line 3: score = score + 4; // add 4
    line 4: score = score - 1; // take away 1
    line 5: show(score); // show it
  36. 36.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let score = 31; // start at 30
    line 2: score = score + 2; // add 2
    line 3: score = score - 4; // take away 4
    line 4: score = score + 3; // add 3
    line 5: show(score); // show it
  37. 37.🐞 What is a good first step when an app gives a wrong result? (a) buy a new phone (b) delete the app (c) find where it goes wrong (d) add more colours
  38. 38.🐞 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 + 2; // add 2
    line 3: score = score + 5; // add 5
    line 4: score = score * 3; // double it
    line 5: show(score); // show it
  39. 39.🐞 This code has a bug. What number does it ACTUALLY show?
    line 1: let coins = 50; // start at 50
    line 2: coins = coins + 6; // add 6
    line 3: coins = coins * 2; // double it
    line 4: coins = coins + 5; // take away 5
    line 5: show(coins); // show it
  40. 40.🐞 Each comment says what its line SHOULD do. Which line has the bug?
    line 1: let points = 46; // start at 45
    line 2: points = points + 5; // add 5
    line 3: points = points * 2; // double it
    line 4: show(points); // show it     (a) line 2 (b) line 1 (c) line 3

Answer key

  1. 94
  2. 87
  3. 30
  4. line 2
  5. a mistake in the code
  6. 48
  7. debugging
  8. people reading the code
  9. 54
  10. line 2
  11. line 1
  12. 80
  13. line 3
  14. 91
  15. 98
  16. line 2
  17. 82
  18. 37
  19. line 2
  20. line 1
  21. 51
  22. 62
  23. 41
  24. test it again
  25. 49
  26. 75
  27. 75
  28. 186
  29. 79
  30. 41
  31. 35
  32. 49
  33. 33
  34. 129
  35. 43
  36. 32
  37. find where it goes wrong
  38. 78
  39. 117
  40. line 1

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