App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 360 · 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.🔁 list.length tells you ___. (a) the first item (b) the biggest item (c) how many items it has (d) the last item
2. 2.🔁 What number does this code show?
   let marks = [1, 13, 11, 5, 12];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
3. 3.🔁 What number does this code show?
   let scores = [12, 4, 10];
   let best = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] > best) {
       best = scores[i];
     }
   }
   show(best);
4. 4.🔁 What is the LAST line this code shows?
   let names = ["Zoya", "Kabir", "Aman", "Riya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman (d) Hi, Zoya
5. 5.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it uses more lines (c) it hides them (d) it is slower
6. 6.🔁 What number does this code show?
   let steps = [20, 4, 15];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
7. 7.🔁 What number does this code show?
   let steps = [61, 65, 53, 61];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
8. 8.🔁 What number does this code show?
   let scores = [17, 1, 5];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
9. 9.🔁 What number does this code show?
   let scores = [73, 63, 27, 57, 11];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 50) {
       count = count + 1;
     }
   }
   show(count);
10. 10.🔁 What number does this code show?
    let scores = [15, 5, 20, 16, 12];
    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 scores = [65, 18, 75, 81, 94];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Meera (c) Hi, Kabir
13. 13.🔁 What does a loop do? (a) saves photos (b) deletes code (c) draws icons (d) repeats code
14. 14.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 6 (c) 5 (d) 4
15. 15.🔁 What number does this code show?
    let runs = [9, 8, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
16. 16.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2 (c) 0, 1, 2, 3 (d) 1, 2, 3
17. 17.🔁 What number does this code show?
    let marks = [15, 5, 15, 20, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
18. 18.🔁 What number does this code show?
    let runs = [15, 54, 62, 93, 12];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
19. 19.🔁 What number does this code show?
    let steps = [12, 20, 16, 6, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
20. 20.🔁 What number does this code show?
    let scores = [99, 77, 62];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
21. 21.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "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, Arjun
22. 22.🔁 What number does this code show?
    let scores = [29, 25, 27];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
23. 23.🔁 What number does this code show?
    let steps = [11, 3, 10, 4];
    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 scores = [11, 53, 35, 16, 16];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let scores = [11, 3, 7, 17, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
26. 26.🔁 What number does this code show?
    let steps = [19, 1, 19, 2, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
27. 27.🔁 What number does this code show?
    let marks = [73, 63, 13, 17];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
28. 28.🔁 What number does this code show?
    let steps = [4, 5, 13, 13, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
29. 29.🔁 What number does this code show?
    let steps = [14, 8, 17];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
30. 30.🔁 What number does this code show?
    let steps = [6, 9, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
31. 31.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
32. 32.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Arjun
33. 33.🔁 What number does this code show?
    let steps = [52, 18, 70, 60];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir
35. 35.🔁 What number does this code show?
    let marks = [12, 15, 17, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
36. 36.🔁 What number does this code show?
    let runs = [43, 62, 12];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let scores = [14, 14, 5, 9, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
38. 38.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Riya (d) Hi, Aman
39. 39.🔁 What number does this code show?
    let runs = [15, 3, 16, 1, 3];
    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 = [96, 36, 69];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

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