App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 32 · 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 = [2, 17, 9, 8];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
2. 2.🔁 What number does this code show?
   let scores = [83, 73, 31, 21];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What number does this code show?
   let runs = [6, 5, 7, 2];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
4. 4.🔁 What number does this code show?
   let scores = [11, 1, 8];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
5. 5.🔁 What number does this code show?
   let marks = [9, 17, 12];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
6. 6.🔁 What number does this code show?
   let steps = [1, 4, 3, 1, 9];
   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 marks = [24, 79, 24, 67];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
8. 8.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 6 (d) 5
9. 9.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it is slower (c) less code to write (d) it uses more lines
10. 10.🔁 What number does this code show?
    let scores = [78, 22, 19, 86];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
11. 11.🔁 What number does this code show?
    let scores = [82, 68, 65, 43];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
13. 13.🔁 list.length tells you ___. (a) how many items it has (b) the biggest item (c) the first item (d) the last item
14. 14.🔁 What number does this code show?
    let marks = [3, 5, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
15. 15.🔁 What number does this code show?
    let scores = [1, 11, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
16. 16.🔁 What does a loop do? (a) repeats code (b) draws icons (c) deletes code (d) saves photos
17. 17.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 3 (d) 0, 1, 2
18. 18.🔁 What number does this code show?
    let runs = [16, 7, 12, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
19. 19.🔁 What number does this code show?
    let marks = [3, 15, 1, 17, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
20. 20.🔁 What number does this code show?
    let marks = [18, 6, 3, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
21. 21.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir (d) Hi, Meera
22. 22.🔁 What number does this code show?
    let scores = [55, 34, 26, 55, 81];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
23. 23.🔁 What number does this code show?
    let scores = [19, 12, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
24. 24.🔁 What number does this code show?
    let marks = [6, 13, 17, 20, 16];
    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 steps = [13, 33, 46, 74];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
26. 26.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Kabir (d) Hi, Riya
27. 27.🔁 What number does this code show?
    let scores = [4, 8, 2];
    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 = ["Aman", "Riya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Arjun (d) Hi, Riya
29. 29.🔁 What number does this code show?
    let marks = [5, 18, 17, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
30. 30.🔁 What number does this code show?
    let scores = [59, 46, 18, 44, 84];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
31. 31.🔁 What number does this code show?
    let marks = [88, 12, 17, 35];
    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 scores = [15, 1, 7, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
33. 33.🔁 What number does this code show?
    let steps = [13, 12, 10, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
34. 34.🔁 What number does this code show?
    let runs = [9, 9, 2, 6, 6];
    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 marks = [65, 38, 73];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Zoya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Riya (c) Hi, Zoya (d) Hi, Arjun
37. 37.🔁 What number does this code show?
    let marks = [4, 11, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
38. 38.🔁 What number does this code show?
    let scores = [12, 4, 2, 4];
    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 scores = [65, 56, 39, 32, 67];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
40. 40.🔁 What number does this code show?
    let marks = [6, 18, 17];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);

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