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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 783 · 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 does a loop do? (a) saves photos (b) draws icons (c) deletes code (d) repeats code
  2. 2.🔁 What number does this code show?
    let steps = [17, 8, 8, 5];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  3. 3.🔁 Why use a loop to show 100 messages? (a) it is slower (b) less code to write (c) it hides them (d) it uses more lines
  4. 4.🔁 What number does this code show?
    let scores = [18, 1, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  5. 5.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 1 (c) 4 (d) 6
  6. 6.🔁 What number does this code show?
    let runs = [69, 52, 32, 30, 11];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [19, 18, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let marks = [7, 8, 10];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Aman", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir (d) Hi, Aman
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya
  11. 11.🔁 What number does this code show?
    let steps = [18, 8, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  12. 12.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 3 (c) 0, 1, 2 (d) 1, 2, 3
  13. 13.🔁 What number does this code show?
    let steps = [20, 15, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let scores = [5, 7, 2, 16, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  15. 15.🔁 What number does this code show?
    let runs = [81, 34, 57, 52, 67];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let scores = [20, 30, 64];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 list.length tells you ___. (a) the first item (b) how many items it has (c) the last item (d) the biggest item
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Zoya
  19. 19.🔁 What number does this code show?
    let scores = [6, 17, 4, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  20. 20.🔁 What number does this code show?
    let scores = [93, 19, 64, 71];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let steps = [93, 27, 66];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let scores = [18, 3, 18, 14, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let marks = [4, 16, 18, 2, 15];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let steps = [89, 35, 95, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let scores = [6, 7, 13, 17, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let scores = [1, 20, 9, 8, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let marks = [16, 1, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Meera
  29. 29.🔁 What number does this code show?
    let runs = [13, 4, 11, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let runs = [19, 20, 14, 9, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let steps = [24, 49, 14, 98, 20];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let steps = [1, 6, 16, 5];
    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 steps = [13, 8, 13, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let scores = [12, 11, 6];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let marks = [3, 6, 3, 20];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Zoya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Riya (d) Hi, Kabir
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Kabir
  38. 38.🔁 What number does this code show?
    let scores = [14, 70, 35];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let runs = [95, 21, 35];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let steps = [17, 49, 14, 76];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. repeats code
  2. 17
  3. less code to write
  4. 35
  5. 5
  6. 0
  7. 50
  8. 10
  9. Hi, Kabir
  10. Hi, Zoya
  11. 41
  12. 0, 1, 2
  13. 20
  14. 41
  15. 2
  16. 1
  17. how many items it has
  18. Hi, Zoya
  19. 17
  20. 2
  21. 2
  22. 18
  23. 18
  24. 2
  25. 17
  26. 20
  27. 16
  28. Hi, Arjun
  29. 13
  30. 82
  31. 2
  32. 28
  33. 13
  34. 29
  35. 20
  36. Hi, Kabir
  37. Hi, Kabir
  38. 1
  39. 1
  40. 1

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