App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 474 · 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 scores = [45, 75, 10, 98];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What does a loop do? (a) deletes code (b) repeats code (c) saves photos (d) draws icons
3. 3.🔁 What number does this code show?
   let runs = [7, 16, 3];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
4. 4.🔁 What is the LAST line this code shows?
   let names = ["Riya", "Zoya", "Arjun"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya
5. 5.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 3 (c) 1, 2, 3 (d) 0, 1, 2
6. 6.🔁 What number does this code show?
   let runs = [10, 5, 2, 14];
   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 steps = [48, 60, 37, 75];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
8. 8.🔁 What number does this code show?
   let marks = [7, 11, 20, 3, 15];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
9. 9.🔁 What number does this code show?
   let marks = [8, 4, 11, 4];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
10. 10.🔁 What number does this code show?
    let steps = [90, 94, 47];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
11. 11.🔁 What number does this code show?
    let scores = [1, 1, 4, 19, 17];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
12. 12.🔁 What number does this code show?
    let steps = [4, 9, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
13. 13.🔁 list.length tells you ___. (a) the last item (b) how many items it has (c) the first item (d) the biggest item
14. 14.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it is slower (d) it uses more lines
15. 15.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Riya (d) Hi, Aman
16. 16.🔁 What number does this code show?
    let scores = [13, 6, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
17. 17.🔁 What number does this code show?
    let steps = [15, 5, 14];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
18. 18.🔁 What number does this code show?
    let scores = [2, 10, 8, 16, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
19. 19.🔁 What number does this code show?
    let runs = [4, 15, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
20. 20.🔁 What number does this code show?
    let runs = [85, 18, 21, 70, 32];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
21. 21.🔁 What number does this code show?
    let steps = [19, 20, 16, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
22. 22.🔁 What number does this code show?
    let scores = [7, 2, 13, 15];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
23. 23.🔁 What number does this code show?
    let runs = [33, 43, 36];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let scores = [1, 10, 6];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
25. 25.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Aman (c) Hi, Meera
26. 26.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 1 (c) 6 (d) 4
27. 27.🔁 What number does this code show?
    let scores = [4, 20, 15];
    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 = ["Riya", "Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Riya
29. 29.🔁 What number does this code show?
    let marks = [13, 3, 13];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
30. 30.🔁 What number does this code show?
    let scores = [5, 1, 4, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
31. 31.🔁 What number does this code show?
    let steps = [36, 25, 63, 83, 51];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
32. 32.🔁 What number does this code show?
    let runs = [8, 1, 2, 7, 10];
    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 = [93, 34, 49];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What number does this code show?
    let marks = [25, 23, 39, 32, 19];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
35. 35.🔁 What number does this code show?
    let scores = [13, 7, 12, 8, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
36. 36.🔁 What number does this code show?
    let runs = [15, 3, 4];
    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 steps = [23, 10, 22, 35];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
38. 38.🔁 What number does this code show?
    let scores = [11, 19, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
39. 39.🔁 What number does this code show?
    let steps = [7, 15, 19];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
40. 40.🔁 What number does this code show?
    let scores = [18, 15, 8, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

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