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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 237 · 40 questions
TalentJR

Developer's tip (One by one): for (let i = 0; i < list.length; i++) visits every item, from position 0. Total: add each item. Count: add 1 when the test is true. Best: keep the biggest so far. The body runs once per item: a list of 5 runs it 5 times.

NameDateTime takenScore ___ / 40
  1. 1.🔁 What number does this code show?
    let scores = [18, 14, 4, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  2. 2.🔁 What number does this code show?
    let scores = [13, 2, 2, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Arjun
  4. 4.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Arjun (d) Hi, Zoya
  5. 5.🔁 What number does this code show?
    let runs = [3, 1, 16, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let marks = [19, 19, 20, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  7. 7.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it is slower (d) it uses more lines
  8. 8.🔁 What does a loop do? (a) repeats code (b) deletes code (c) draws icons (d) saves photos
  9. 9.🔁 What number does this code show?
    let scores = [19, 7, 10, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Aman (d) Hi, Riya
  11. 11.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 3
  12. 12.🔁 What number does this code show?
    let steps = [5, 3, 16, 18, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya
  14. 14.🔁 What number does this code show?
    let scores = [25, 89, 64, 98, 60];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let runs = [91, 20, 68];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let marks = [20, 11, 12, 11, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let runs = [14, 4, 1, 18];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let steps = [17, 3, 3, 3, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let steps = [46, 32, 87, 67];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let runs = [10, 16, 1, 2, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let runs = [5, 16, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Arjun
  23. 23.🔁 list.length tells you ___. (a) the last item (b) how many items it has (c) the first item (d) the biggest item
  24. 24.🔁 What number does this code show?
    let scores = [19, 10, 1, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [3, 1, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let steps = [17, 11, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Meera (d) Hi, Zoya
  28. 28.🔁 What number does this code show?
    let runs = [16, 19, 13, 1, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let scores = [4, 10, 11];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let marks = [37, 98, 35, 97, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What number does this code show?
    let marks = [4, 3, 5, 15];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let steps = [14, 3, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let marks = [12, 74, 87, 84, 55];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 5 (d) 4
  35. 35.🔁 What number does this code show?
    let steps = [72, 31, 96, 51];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let runs = [14, 19, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let steps = [7, 11, 12, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let runs = [17, 13, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let steps = [4, 7, 6, 6, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let runs = [2, 20, 4, 10];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);

Answer key

  1. 52
  2. 19
  3. Hi, Zoya
  4. Hi, Arjun
  5. 16
  6. 20
  7. less code to write
  8. repeats code
  9. 53
  10. Hi, Aman
  11. 0, 1, 2
  12. 18
  13. Hi, Aman
  14. 4
  15. 2
  16. 20
  17. 18
  18. 33
  19. 3
  20. 32
  21. 22
  22. Hi, Riya
  23. how many items it has
  24. 38
  25. 18
  26. 17
  27. Hi, Riya
  28. 19
  29. 11
  30. 2
  31. 15
  32. 28
  33. 4
  34. 5
  35. 3
  36. 45
  37. 45
  38. 50
  39. 43
  40. 20

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