App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 544 · 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 = [27, 21, 16, 60];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 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
3. 3.🔁 What number does this code show?
   let runs = [26, 17, 86, 15];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
4. 4.🔁 What number does this code show?
   let runs = [9, 4, 17];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
5. 5.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it is slower (c) it hides them (d) it uses more lines
6. 6.🔁 What number does this code show?
   let steps = [19, 16, 10];
   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 marks = [20, 10, 16, 6];
   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 scores = [8, 8, 11, 8, 11];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
9. 9.🔁 What number does this code show?
   let steps = [16, 1, 12, 8, 7];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
10. 10.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 6 (d) 1
11. 11.🔁 What number does this code show?
    let scores = [2, 5, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya
13. 13.🔁 What number does this code show?
    let scores = [3, 2, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
14. 14.🔁 What number does this code show?
    let marks = [88, 99, 38, 84];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let runs = [67, 38, 75];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
16. 16.🔁 What number does this code show?
    let runs = [1, 7, 14, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
17. 17.🔁 What number does this code show?
    let marks = [12, 9, 3, 3, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
18. 18.🔁 What number does this code show?
    let scores = [81, 35, 37];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
19. 19.🔁 What number does this code show?
    let scores = [2, 17, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
20. 20.🔁 What number does this code show?
    let marks = [16, 18, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
21. 21.🔁 What number does this code show?
    let marks = [16, 63, 30, 42, 73];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
22. 22.🔁 What number does this code show?
    let steps = [67, 17, 80, 17];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
23. 23.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
24. 24.🔁 What number does this code show?
    let marks = [11, 15, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
25. 25.🔁 What number does this code show?
    let runs = [12, 1, 3, 4];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
26. 26.🔁 What number does this code show?
    let steps = [5, 17, 11, 5];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
27. 27.🔁 What number does this code show?
    let steps = [15, 11, 3, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
29. 29.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Arjun (c) Hi, Meera (d) Hi, Kabir
30. 30.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Riya (d) Hi, Meera
31. 31.🔁 What number does this code show?
    let marks = [17, 14, 4, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
32. 32.🔁 What number does this code show?
    let scores = [13, 11, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
33. 33.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Aman
34. 34.🔁 What does a loop do? (a) deletes code (b) draws icons (c) repeats code (d) saves photos
35. 35.🔁 What number does this code show?
    let marks = [90, 57, 39, 89, 97];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let runs = [34, 66, 42, 16, 36];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let runs = [16, 14, 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 steps = [6, 12, 15, 10, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
39. 39.🔁 What number does this code show?
    let steps = [5, 7, 5, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
40. 40.🔁 What number does this code show?
    let steps = [16, 19, 2, 14, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);

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