App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 126 · 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 = [33, 29, 55, 27, 87];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What number does this code show?
   let runs = [27, 35, 75, 36, 60];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What does a loop do? (a) draws icons (b) saves photos (c) repeats code (d) deletes code
4. 4.🔁 What number does this code show?
   let marks = [18, 79, 11];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What number does this code show?
   let marks = [1, 4, 12];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
6. 6.🔁 What is the LAST line this code shows?
   let names = ["Kabir", "Arjun", "Zoya", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Aman (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Kabir
7. 7.🔁 What number does this code show?
   let scores = [14, 2, 20, 3];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
8. 8.🔁 What number does this code show?
   let steps = [97, 95, 22, 71];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
9. 9.🔁 What number does this code show?
   let runs = [20, 1, 17];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
10. 10.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) less code to write (d) it hides them
11. 11.🔁 What number does this code show?
    let runs = [9, 3, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
12. 12.🔁 What number does this code show?
    let steps = [19, 18, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
13. 13.🔁 What number does this code show?
    let scores = [5, 19, 19, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
14. 14.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 5 (d) 4
15. 15.🔁 What number does this code show?
    let runs = [17, 18, 53];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
16. 16.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Riya", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
17. 17.🔁 What number does this code show?
    let scores = [4, 20, 20, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
18. 18.🔁 What number does this code show?
    let marks = [13, 8, 14, 9];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Aman (d) Hi, Zoya
20. 20.🔁 What number does this code show?
    let runs = [19, 19, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
21. 21.🔁 What number does this code show?
    let steps = [3, 6, 5, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
22. 22.🔁 What number does this code show?
    let scores = [13, 15, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
23. 23.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Zoya
24. 24.🔁 What number does this code show?
    let runs = [5, 9, 11, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
25. 25.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Meera (c) Hi, Kabir (d) Hi, Zoya
26. 26.🔁 What number does this code show?
    let scores = [29, 63, 59, 71];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 What number does this code show?
    let marks = [7, 15, 20, 11, 17];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
29. 29.🔁 What number does this code show?
    let scores = [5, 19, 15, 17];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
30. 30.🔁 list.length tells you ___. (a) the first item (b) the last item (c) how many items it has (d) the biggest item
31. 31.🔁 What number does this code show?
    let scores = [5, 12, 2, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
32. 32.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Kabir
33. 33.🔁 What number does this code show?
    let scores = [36, 88, 48];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What number does this code show?
    let marks = [77, 18, 61, 20, 47];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
35. 35.🔁 What number does this code show?
    let scores = [42, 40, 57];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let steps = [69, 31, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let marks = [66, 88, 14, 48];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
38. 38.🔁 What number does this code show?
    let scores = [14, 20, 1, 5, 17];
    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 marks = [4, 16, 15, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
40. 40.🔁 What number does this code show?
    let runs = [2, 9, 3, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);

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