App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 618 · 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.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 5 (d) 6
2. 2.🔁 What number does this code show?
   let marks = [19, 9, 7];
   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 runs = [4, 16, 8];
   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 runs = [27, 56, 16];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What number does this code show?
   let marks = [21, 67, 61, 90];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
6. 6.🔁 What number does this code show?
   let steps = [16, 11, 14];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
7. 7.🔁 What number does this code show?
   let steps = [27, 63, 57, 44, 60];
   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 steps = [5, 13, 6, 5, 11];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
9. 9.🔁 What number does this code show?
   let marks = [5, 14, 19];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
10. 10.🔁 What number does this code show?
    let steps = [20, 1, 15, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
11. 11.🔁 What number does this code show?
    let marks = [19, 16, 15, 15, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
12. 12.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) less code to write (c) it is slower (d) it hides them
13. 13.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Aman (c) Hi, Meera (d) Hi, Arjun
14. 14.🔁 What number does this code show?
    let runs = [52, 32, 85, 14];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let runs = [6, 1, 5, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
16. 16.🔁 What number does this code show?
    let steps = [10, 1, 9, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
17. 17.🔁 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, Meera (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Riya
18. 18.🔁 What number does this code show?
    let steps = [4, 14, 5, 8];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
19. 19.🔁 What does a loop do? (a) saves photos (b) repeats code (c) draws icons (d) deletes code
20. 20.🔁 What number does this code show?
    let runs = [19, 20, 6, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
21. 21.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 0, 1, 2, 3
22. 22.🔁 What number does this code show?
    let marks = [16, 15, 18, 5, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
23. 23.🔁 What number does this code show?
    let marks = [94, 55, 31];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let marks = [2, 20, 19, 8, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
25. 25.🔁 What number does this code show?
    let scores = [2, 1, 10];
    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 marks = [20, 18, 12, 1, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
27. 27.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Zoya", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Meera (c) Hi, Zoya (d) Hi, Riya
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Meera (c) Hi, Aman (d) Hi, Kabir
29. 29.🔁 list.length tells you ___. (a) the last item (b) how many items it has (c) the biggest item (d) the first item
30. 30.🔁 What number does this code show?
    let scores = [11, 16, 10];
    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 scores = [16, 7, 4, 7, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
32. 32.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Meera (c) Hi, Arjun
33. 33.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Meera (c) Hi, Aman (d) Hi, Zoya
34. 34.🔁 What number does this code show?
    let steps = [19, 13, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
35. 35.🔁 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, Kabir (c) Hi, Zoya (d) Hi, Aman
36. 36.🔁 What number does this code show?
    let scores = [20, 12, 2, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
37. 37.🔁 What number does this code show?
    let scores = [75, 10, 42];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
38. 38.🔁 What number does this code show?
    let scores = [17, 2, 2, 20, 6];
    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 marks = [3, 1, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
40. 40.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Aman (c) Hi, Zoya

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