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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 658 · 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.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) it uses more lines (d) less code to write
  2. 2.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 6 (c) 5 (d) 4
  3. 3.🔁 What number does this code show?
    let marks = [7, 11, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let marks = [7, 20, 7, 8, 15];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Riya
  6. 6.🔁 What number does this code show?
    let scores = [12, 8, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir
  8. 8.🔁 What number does this code show?
    let marks = [17, 11, 8, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let steps = [2, 1, 11, 10, 3];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  10. 10.🔁 What number does this code show?
    let scores = [3, 5, 3, 18];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  11. 11.🔁 What number does this code show?
    let steps = [12, 18, 16, 16, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let scores = [20, 4, 13, 1, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let steps = [9, 4, 10, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  14. 14.🔁 What number does this code show?
    let steps = [9, 12, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Riya
  16. 16.🔁 What number does this code show?
    let marks = [18, 5, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Arjun
  18. 18.🔁 What number does this code show?
    let steps = [9, 14, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  19. 19.🔁 What does a loop do? (a) repeats code (b) draws icons (c) saves photos (d) deletes code
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Arjun
  21. 21.🔁 What number does this code show?
    let steps = [92, 90, 68];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let marks = [19, 3, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Riya
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
  25. 25.🔁 What number does this code show?
    let marks = [3, 16, 13, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let runs = [20, 12, 1, 3];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let scores = [13, 9, 9, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  28. 28.🔁 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
  29. 29.🔁 What number does this code show?
    let scores = [20, 6, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let runs = [5, 19, 12];
    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 scores = [28, 84, 45];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let marks = [18, 9, 3, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let scores = [9, 18, 11, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let marks = [16, 18, 4, 3, 11];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let marks = [61, 50, 19, 50];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let marks = [96, 26, 55];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let steps = [2, 4, 6, 16];
    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 = [9, 2, 12, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
  40. 40.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has

Answer key

  1. less code to write
  2. 5
  3. 30
  4. 20
  5. Hi, Meera
  6. 39
  7. Hi, Kabir
  8. 17
  9. 11
  10. 29
  11. 78
  12. 45
  13. 33
  14. 38
  15. Hi, Riya
  16. 18
  17. Hi, Arjun
  18. 14
  19. repeats code
  20. Hi, Aman
  21. 3
  22. 19
  23. Hi, Zoya
  24. Hi, Aman
  25. 38
  26. 20
  27. 13
  28. 0, 1, 2
  29. 35
  30. 36
  31. 1
  32. 18
  33. 18
  34. 18
  35. 0
  36. 2
  37. 28
  38. 25
  39. Hi, Riya
  40. how many items it has

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