App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 106 · 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 marks = [21, 81, 83, 44];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What does a loop do? (a) repeats code (b) saves photos (c) draws icons (d) deletes code
3. 3.🔁 What is the LAST line this code shows?
   let names = ["Riya", "Kabir", "Zoya", "Aman", "Arjun"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Riya
4. 4.🔁 What number does this code show?
   let steps = [70, 79, 55, 12];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What number does this code show?
   let runs = [3, 20, 2, 7];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
6. 6.🔁 What is the LAST line this code shows?
   let names = ["Aman", "Riya", "Zoya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman
7. 7.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 1, 2, 3
8. 8.🔁 What number does this code show?
   let scores = [17, 3, 5];
   let best = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] > best) {
       best = scores[i];
     }
   }
   show(best);
9. 9.🔁 What number does this code show?
   let marks = [1, 3, 3, 2, 6];
   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 scores = [20, 1, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
11. 11.🔁 What number does this code show?
    let marks = [14, 2, 4, 7, 2];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
12. 12.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir
13. 13.🔁 What number does this code show?
    let marks = [97, 20, 26, 50];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
14. 14.🔁 What number does this code show?
    let runs = [4, 20, 2, 13, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
15. 15.🔁 What number does this code show?
    let runs = [7, 1, 19];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
16. 16.🔁 What number does this code show?
    let runs = [25, 19, 65, 41, 41];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 6 (d) 5
18. 18.🔁 What number does this code show?
    let scores = [18, 17, 3, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
19. 19.🔁 list.length tells you ___. (a) the first item (b) the last item (c) the biggest item (d) how many items it has
20. 20.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Aman (c) Hi, Riya
21. 21.🔁 What number does this code show?
    let scores = [13, 10, 17];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
22. 22.🔁 What number does this code show?
    let runs = [14, 5, 6, 20, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
23. 23.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
24. 24.🔁 What number does this code show?
    let scores = [4, 7, 20, 10, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
25. 25.🔁 What number does this code show?
    let scores = [15, 81, 41];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
26. 26.🔁 What number does this code show?
    let runs = [96, 59, 50, 57, 92];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 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
28. 28.🔁 What number does this code show?
    let steps = [3, 18, 15, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
29. 29.🔁 What number does this code show?
    let steps = [76, 13, 39];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
30. 30.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Riya
31. 31.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Arjun
32. 32.🔁 What number does this code show?
    let runs = [16, 4, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
33. 33.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Kabir (c) Hi, Meera
34. 34.🔁 What number does this code show?
    let steps = [13, 11, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
35. 35.🔁 What number does this code show?
    let marks = [67, 48, 97];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let steps = [14, 20, 20, 14, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
37. 37.🔁 What number does this code show?
    let scores = [44, 42, 50];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
38. 38.🔁 What number does this code show?
    let runs = [13, 61, 76, 54, 43];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
39. 39.🔁 What number does this code show?
    let runs = [9, 12, 10];
    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 runs = [20, 12, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

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