App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 426 · 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 = [98, 28, 66];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What number does this code show?
   let scores = [14, 10, 5, 11, 12];
   let best = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] > best) {
       best = scores[i];
     }
   }
   show(best);
3. 3.🔁 list.length tells you ___. (a) how many items it has (b) the biggest item (c) the last item (d) the first item
4. 4.🔁 What is the LAST line this code shows?
   let names = ["Kabir", "Arjun", "Riya", "Zoya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Riya
5. 5.🔁 What does a loop do? (a) repeats code (b) deletes code (c) saves photos (d) draws icons
6. 6.🔁 What number does this code show?
   let marks = [13, 15, 16];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
7. 7.🔁 What number does this code show?
   let marks = [7, 6, 8];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
8. 8.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 1 (d) 6
9. 9.🔁 What number does this code show?
   let runs = [68, 84, 91, 15];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
10. 10.🔁 What number does this code show?
    let scores = [75, 54, 75, 40, 32];
    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 = [34, 40, 17, 43];
    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 steps = [13, 50, 72, 35];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
13. 13.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) less code to write (c) it hides them (d) it is slower
14. 14.🔁 What number does this code show?
    let steps = [36, 82, 39, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Aman (c) Hi, Zoya
16. 16.🔁 What number does this code show?
    let steps = [39, 76, 67, 56, 16];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What number does this code show?
    let runs = [2, 7, 5, 2, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
18. 18.🔁 What number does this code show?
    let steps = [27, 28, 41];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
19. 19.🔁 What number does this code show?
    let scores = [94, 14, 46];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
20. 20.🔁 What number does this code show?
    let scores = [15, 11, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
21. 21.🔁 What number does this code show?
    let scores = [15, 13, 7, 6, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
22. 22.🔁 What number does this code show?
    let marks = [12, 4, 19, 15, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
23. 23.🔁 What number does this code show?
    let marks = [35, 74, 53];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let scores = [75, 59, 65, 13];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let scores = [4, 14, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
26. 26.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Aman", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Arjun
27. 27.🔁 What number does this code show?
    let scores = [19, 7, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Kabir", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Aman
29. 29.🔁 What number does this code show?
    let steps = [7, 16, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
30. 30.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Riya (d) Hi, Meera
31. 31.🔁 What number does this code show?
    let marks = [73, 66, 98];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
32. 32.🔁 What number does this code show?
    let steps = [78, 88, 14, 90, 15];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
33. 33.🔁 What number does this code show?
    let steps = [6, 6, 5, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
34. 34.🔁 What number does this code show?
    let runs = [5, 3, 18, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
35. 35.🔁 What number does this code show?
    let steps = [74, 16, 65, 27, 15];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let runs = [17, 11, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
37. 37.🔁 What number does this code show?
    let marks = [8, 19, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
38. 38.🔁 What number does this code show?
    let runs = [9, 5, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
39. 39.🔁 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
40. 40.🔁 What number does this code show?
    let runs = [10, 18, 13, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

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