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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 821 · 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 is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Kabir
  2. 2.🔁 What does a loop do? (a) repeats code (b) saves photos (c) draws icons (d) deletes code
  3. 3.🔁 What number does this code show?
    let steps = [14, 19, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let runs = [11, 2, 2, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  5. 5.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 3 (c) 0, 1, 2, 3 (d) 0, 1, 2
  6. 6.🔁 What number does this code show?
    let steps = [86, 85, 17, 85];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let steps = [12, 11, 5, 8, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Aman", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Arjun (d) Hi, Zoya
  9. 9.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 6 (c) 1 (d) 4
  10. 10.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
  11. 11.🔁 What number does this code show?
    let scores = [7, 3, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Arjun (d) Hi, Riya
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman
  14. 14.🔁 What number does this code show?
    let runs = [6, 6, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  15. 15.🔁 What number does this code show?
    let steps = [2, 9, 7, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let scores = [2, 5, 2, 20, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Riya", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Arjun
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Zoya
  19. 19.🔁 What number does this code show?
    let scores = [11, 3, 7];
    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 runs = [81, 95, 52, 93];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let marks = [18, 3, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let scores = [11, 16, 1, 4, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let scores = [18, 14, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let marks = [95, 75, 33, 86];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let runs = [72, 57, 54, 58];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let marks = [11, 42, 84, 82];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let steps = [8, 12, 9, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let steps = [9, 4, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let runs = [15, 19, 9, 13, 13];
    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 marks = [14, 2, 15];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let scores = [16, 3, 17];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  32. 32.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it is slower (c) it uses more lines (d) less code to write
  33. 33.🔁 What number does this code show?
    let steps = [93, 92, 80, 14, 28];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Meera", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Meera (d) Hi, Aman
  35. 35.🔁 What number does this code show?
    let steps = [17, 7, 15, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Riya
  37. 37.🔁 What number does this code show?
    let steps = [12, 2, 13, 11, 3];
    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 steps = [4, 4, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [13, 17, 4, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let marks = [14, 4, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);

Answer key

  1. Hi, Kabir
  2. repeats code
  3. 45
  4. 33
  5. 0, 1, 2
  6. 3
  7. 39
  8. Hi, Zoya
  9. 5
  10. how many items it has
  11. 24
  12. Hi, Riya
  13. Hi, Meera
  14. 27
  15. 25
  16. 41
  17. Hi, Meera
  18. Hi, Zoya
  19. 11
  20. 4
  21. 18
  22. 51
  23. 36
  24. 3
  25. 4
  26. 3
  27. 12
  28. 9
  29. 19
  30. 15
  31. 17
  32. less code to write
  33. 3
  34. Hi, Riya
  35. 18
  36. Hi, Riya
  37. 41
  38. 17
  39. 40
  40. 14

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