App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 100 · 40 questions

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.

1. 1.🔁 What number does this code show?
   let marks = [22, 68, 14, 10];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 5 (d) 4
3. 3.🔁 What is the LAST line this code shows?
   let names = ["Riya", "Kabir", "Zoya", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
4. 4.🔁 What does a loop do? (a) saves photos (b) draws icons (c) deletes code (d) repeats code
5. 5.🔁 What number does this code show?
   let scores = [17, 1, 6, 9];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
6. 6.🔁 What is the LAST line this code shows?
   let names = ["Zoya", "Kabir", "Riya", "Meera", "Arjun"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Riya (d) Hi, Arjun
7. 7.🔁 What is the LAST line this code shows?
   let names = ["Arjun", "Kabir", "Meera", "Aman", "Riya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Arjun (b) Hi, Riya (c) Hi, Meera (d) Hi, Kabir
8. 8.🔁 What is the LAST line this code shows?
   let names = ["Aman", "Zoya", "Arjun", "Meera", "Kabir"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Zoya (b) Hi, Aman (c) Hi, Arjun (d) Hi, Kabir
9. 9.🔁 What number does this code show?
   let runs = [28, 12, 58];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
10. 10.🔁 What number does this code show?
    let scores = [8, 15, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
11. 11.🔁 What number does this code show?
    let runs = [5, 18, 6, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
12. 12.🔁 What number does this code show?
    let marks = [45, 32, 96];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
13. 13.🔁 What number does this code show?
    let runs = [4, 12, 5, 15, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
14. 14.🔁 What number does this code show?
    let steps = [26, 25, 64];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let runs = [12, 4, 18, 13, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
16. 16.🔁 What number does this code show?
    let steps = [15, 50, 85, 53, 76];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What number does this code show?
    let runs = [6, 9, 3, 13, 17];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
18. 18.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) less code to write (d) it uses more lines
19. 19.🔁 list.length tells you ___. (a) how many items it has (b) the last item (c) the biggest item (d) the first item
20. 20.🔁 What number does this code show?
    let steps = [14, 17, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
21. 21.🔁 What number does this code show?
    let scores = [5, 15, 2, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
22. 22.🔁 What number does this code show?
    let steps = [76, 70, 64, 78];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
23. 23.🔁 What number does this code show?
    let steps = [16, 15, 16, 19];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
24. 24.🔁 What number does this code show?
    let marks = [35, 12, 53];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 1, 2, 3 (c) 3 (d) 0, 1, 2
26. 26.🔁 What number does this code show?
    let steps = [60, 32, 84, 60, 30];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 What number does this code show?
    let scores = [2, 1, 14, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
28. 28.🔁 What number does this code show?
    let marks = [13, 15, 14, 8, 20];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
29. 29.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Zoya
30. 30.🔁 What number does this code show?
    let scores = [14, 5, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
31. 31.🔁 What number does this code show?
    let marks = [10, 14, 8];
    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 runs = [7, 20, 4];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
33. 33.🔁 What number does this code show?
    let scores = [7, 11, 13, 2, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
34. 34.🔁 What number does this code show?
    let steps = [11, 20, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
35. 35.🔁 What number does this code show?
    let steps = [9, 1, 12, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
36. 36.🔁 What number does this code show?
    let runs = [29, 35, 21, 84];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let steps = [12, 13, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
38. 38.🔁 What number does this code show?
    let steps = [13, 4, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
39. 39.🔁 What number does this code show?
    let runs = [4, 17, 10];
    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 runs = [6, 16, 12, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);

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