App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 813 · 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 = [95, 92, 85, 42];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What number does this code show?
   let marks = [19, 1, 6, 1];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
3. 3.🔁 What number does this code show?
   let marks = [6, 14, 9, 10];
   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 = [16, 3, 19, 19];
   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 = [2, 1, 4];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
6. 6.🔁 What number does this code show?
   let runs = [1, 19, 3, 13, 8];
   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 marks = [12, 14, 15];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
8. 8.🔁 What number does this code show?
   let steps = [7, 13, 20, 11, 18];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
9. 9.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 5 (d) 6
10. 10.🔁 What number does this code show?
    let scores = [15, 5, 11, 9, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
11. 11.🔁 What number does this code show?
    let marks = [18, 88, 18, 41];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it uses more lines (c) it is slower (d) it hides them
13. 13.🔁 What number does this code show?
    let runs = [14, 14, 3, 5, 16];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
14. 14.🔁 What number does this code show?
    let scores = [1, 7, 6, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
15. 15.🔁 What number does this code show?
    let scores = [1, 18, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
16. 16.🔁 What number does this code show?
    let marks = [39, 28, 52, 53];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Aman
18. 18.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Riya (c) Hi, Meera (d) Hi, Zoya
19. 19.🔁 What does a loop do? (a) repeats code (b) saves photos (c) draws icons (d) deletes code
20. 20.🔁 What number does this code show?
    let steps = [17, 18, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
21. 21.🔁 What number does this code show?
    let steps = [70, 86, 17];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
22. 22.🔁 What number does this code show?
    let steps = [12, 1, 4];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
23. 23.🔁 What number does this code show?
    let steps = [9, 19, 3, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
24. 24.🔁 What number does this code show?
    let runs = [31, 63, 13, 44, 96];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 list.length tells you ___. (a) the first item (b) the last item (c) the biggest item (d) how many items it has
26. 26.🔁 What number does this code show?
    let marks = [10, 4, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
27. 27.🔁 What number does this code show?
    let runs = [89, 51, 73, 83, 90];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
28. 28.🔁 What number does this code show?
    let steps = [1, 18, 17, 1, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
29. 29.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman
30. 30.🔁 What number does this code show?
    let scores = [11, 10, 13, 12];
    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 = [18, 13, 7, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
32. 32.🔁 What number does this code show?
    let steps = [18, 5, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
33. 33.🔁 What number does this code show?
    let runs = [99, 13, 47, 12, 41];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What number does this code show?
    let scores = [13, 13, 6, 11, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
35. 35.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
36. 36.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Aman
37. 37.🔁 What number does this code show?
    let marks = [14, 11, 1, 5];
    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 steps = [1, 13, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
39. 39.🔁 What number does this code show?
    let scores = [41, 34, 67, 84];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
40. 40.🔁 What number does this code show?
    let steps = [5, 10, 3, 16, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);

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