App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 799 · 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) 5 (b) 1 (c) 4 (d) 6
2. 2.🔁 What number does this code show?
   let steps = [34, 72, 55];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What number does this code show?
   let marks = [9, 16, 20, 14, 15];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
4. 4.🔁 What number does this code show?
   let scores = [37, 24, 94, 14];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 list.length tells you ___. (a) the last item (b) the first item (c) the biggest item (d) how many items it has
6. 6.🔁 What number does this code show?
   let runs = [2, 17, 11];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
7. 7.🔁 What does a loop do? (a) draws icons (b) saves photos (c) deletes code (d) repeats code
8. 8.🔁 What number does this code show?
   let scores = [73, 27, 10, 68, 84];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 50) {
       count = count + 1;
     }
   }
   show(count);
9. 9.🔁 What number does this code show?
   let steps = [9, 8, 10, 19];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
10. 10.🔁 What number does this code show?
    let runs = [32, 55, 49, 71];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
11. 11.🔁 What number does this code show?
    let scores = [18, 13, 19, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
12. 12.🔁 What number does this code show?
    let runs = [8, 19, 11, 1];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
13. 13.🔁 What number does this code show?
    let scores = [69, 20, 41];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
14. 14.🔁 What number does this code show?
    let marks = [3, 5, 15, 2, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
15. 15.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) less code to write (d) it uses more lines
16. 16.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Aman", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Aman
17. 17.🔁 What number does this code show?
    let runs = [20, 3, 5];
    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 = [9, 12, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
19. 19.🔁 What number does this code show?
    let marks = [15, 19, 14, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
20. 20.🔁 What number does this code show?
    let steps = [10, 2, 17, 4, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
21. 21.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Meera
22. 22.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Riya
23. 23.🔁 What number does this code show?
    let steps = [4, 15, 8, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
24. 24.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2 (d) 0, 1, 2, 3
25. 25.🔁 What number does this code show?
    let steps = [13, 20, 9, 6, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
26. 26.🔁 What number does this code show?
    let runs = [16, 63, 34, 38];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Meera
28. 28.🔁 What number does this code show?
    let marks = [2, 1, 13, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
29. 29.🔁 What number does this code show?
    let scores = [13, 1, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
30. 30.🔁 What number does this code show?
    let scores = [12, 20, 20, 15];
    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 = [14, 13, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
32. 32.🔁 What number does this code show?
    let runs = [2, 1, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
33. 33.🔁 What number does this code show?
    let marks = [10, 15, 2, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
34. 34.🔁 What number does this code show?
    let steps = [12, 15, 4, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
35. 35.🔁 What number does this code show?
    let steps = [3, 15, 16];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
36. 36.🔁 What number does this code show?
    let scores = [15, 18, 15];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
37. 37.🔁 What number does this code show?
    let runs = [4, 20, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
38. 38.🔁 What number does this code show?
    let marks = [3, 15, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
39. 39.🔁 What number does this code show?
    let scores = [25, 13, 22, 24];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
40. 40.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Zoya

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