App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 127 · 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 steps = [10, 14, 2, 6, 17];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
2. 2.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 1, 2, 3
3. 3.🔁 What number does this code show?
   let runs = [11, 6, 12];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
4. 4.🔁 What number does this code show?
   let scores = [92, 86, 16, 14, 68];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What does a loop do? (a) deletes code (b) saves photos (c) draws icons (d) repeats code
6. 6.🔁 What number does this code show?
   let runs = [16, 8, 12, 17, 10];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
7. 7.🔁 What number does this code show?
   let runs = [9, 18, 8, 1];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
8. 8.🔁 What number does this code show?
   let steps = [14, 9, 2];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
9. 9.🔁 What is the LAST line this code shows?
   let names = ["Arjun", "Kabir", "Riya", "Meera"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Arjun
10. 10.🔁 What number does this code show?
    let scores = [26, 69, 90];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
11. 11.🔁 What number does this code show?
    let runs = [14, 60, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 What number does this code show?
    let marks = [15, 9, 15, 16, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
13. 13.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Arjun", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
14. 14.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) it is slower (d) less code to write
15. 15.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 6 (d) 1
16. 16.🔁 What number does this code show?
    let steps = [11, 13, 3, 6, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
17. 17.🔁 What number does this code show?
    let marks = [10, 13, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
18. 18.🔁 What number does this code show?
    let steps = [14, 8, 1, 1, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
19. 19.🔁 list.length tells you ___. (a) the last item (b) the first item (c) the biggest item (d) how many items it has
20. 20.🔁 What number does this code show?
    let scores = [45, 11, 35, 73];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
21. 21.🔁 What number does this code show?
    let steps = [76, 45, 17, 36, 21];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
22. 22.🔁 What number does this code show?
    let scores = [15, 12, 1];
    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 steps = [29, 16, 36, 44, 84];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
25. 25.🔁 What number does this code show?
    let scores = [19, 44, 52, 34];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
26. 26.🔁 What number does this code show?
    let marks = [7, 5, 1, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
27. 27.🔁 What number does this code show?
    let steps = [6, 4, 4, 10, 9];
    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 marks = [44, 70, 21];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
29. 29.🔁 What number does this code show?
    let runs = [18, 1, 16, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
30. 30.🔁 What number does this code show?
    let scores = [1, 4, 3];
    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 runs = [12, 3, 1, 12, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
32. 32.🔁 What number does this code show?
    let scores = [4, 18, 6, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
33. 33.🔁 What number does this code show?
    let scores = [11, 14, 20, 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 marks = [15, 16, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
35. 35.🔁 What number does this code show?
    let steps = [74, 25, 46];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let marks = [4, 10, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
37. 37.🔁 What number does this code show?
    let runs = [16, 17, 15];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
38. 38.🔁 What number does this code show?
    let steps = [10, 6, 9, 20];
    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, 20, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
40. 40.🔁 What number does this code show?
    let scores = [34, 25, 29, 72];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);

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