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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 353 · 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 hides them (b) less code to write (c) it uses more lines (d) it is slower
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Riya
  3. 3.🔁 What number does this code show?
    let marks = [15, 72, 27, 28];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let scores = [1, 5, 17, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  5. 5.🔁 What does a loop do? (a) repeats code (b) saves photos (c) deletes code (d) draws icons
  6. 6.🔁 What number does this code show?
    let scores = [10, 6, 17, 2];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Aman
  8. 8.🔁 What number does this code show?
    let marks = [9, 5, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  9. 9.🔁 What number does this code show?
    let scores = [18, 5, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  10. 10.🔁 What number does this code show?
    let runs = [14, 16, 93, 58];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Riya (d) Hi, Arjun
  12. 12.🔁 What number does this code show?
    let scores = [19, 9, 4];
    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 runs = [12, 19, 2, 3, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Kabir (d) Hi, Riya
  15. 15.🔁 What number does this code show?
    let scores = [12, 20, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let scores = [5, 11, 19, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Kabir (d) Hi, Riya
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Kabir
  19. 19.🔁 What number does this code show?
    let marks = [3, 20, 2, 18, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  20. 20.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 5 (c) 6 (d) 4
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Meera", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Riya (d) Hi, Meera
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Kabir", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Riya (d) Hi, Kabir
  23. 23.🔁 What number does this code show?
    let marks = [70, 91, 13, 99, 28];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let marks = [15, 14, 12, 14, 19];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [17, 4, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  26. 26.🔁 list.length tells you ___. (a) the last item (b) the first item (c) how many items it has (d) the biggest item
  27. 27.🔁 What number does this code show?
    let scores = [22, 14, 74];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 1, 2, 3
  29. 29.🔁 What number does this code show?
    let scores = [24, 10, 60, 55, 29];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let runs = [15, 4, 6, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
  32. 32.🔁 What number does this code show?
    let steps = [11, 67, 25, 51, 18];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let marks = [14, 5, 16];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let scores = [3, 6, 1, 19];
    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 runs = [64, 28, 88, 57, 56];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let steps = [13, 9, 4, 4];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Zoya", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Kabir
  38. 38.🔁 What number does this code show?
    let marks = [16, 11, 16];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let runs = [1, 18, 14, 9, 9];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  40. 40.🔁 What number does this code show?
    let marks = [19, 79, 88, 46, 22];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. less code to write
  2. Hi, Kabir
  3. 1
  4. 17
  5. repeats code
  6. 17
  7. Hi, Meera
  8. 17
  9. 31
  10. 1
  11. Hi, Arjun
  12. 32
  13. 19
  14. Hi, Kabir
  15. 20
  16. 19
  17. Hi, Kabir
  18. Hi, Meera
  19. 49
  20. 5
  21. Hi, Riya
  22. Hi, Riya
  23. 3
  24. 74
  25. 33
  26. how many items it has
  27. 1
  28. 0, 1, 2
  29. 0
  30. 39
  31. Hi, Kabir
  32. 2
  33. 16
  34. 29
  35. 4
  36. 13
  37. Hi, Arjun
  38. 16
  39. 18
  40. 3

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