App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 811 · 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 steps = [2, 8, 6, 13, 16];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
2. 2.🔁 What number does this code show?
   let runs = [84, 41, 91, 19];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What number does this code show?
   let marks = [4, 7, 4, 14];
   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 steps = [10, 3, 14];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
5. 5.🔁 What number does this code show?
   let scores = [35, 43, 50];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
6. 6.🔁 What is the LAST line this code shows?
   let names = ["Zoya", "Riya", "Meera", "Arjun", "Kabir"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Meera
7. 7.🔁 What is the LAST line this code shows?
   let names = ["Meera", "Zoya", "Arjun"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Meera (b) Hi, Arjun (c) Hi, Zoya
8. 8.🔁 What is the LAST line this code shows?
   let names = ["Aman", "Zoya", "Riya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Aman (b) Hi, Riya (c) Hi, Zoya
9. 9.🔁 What does a loop do? (a) repeats code (b) saves photos (c) deletes code (d) draws icons
10. 10.🔁 What number does this code show?
    let marks = [13, 18, 20, 20];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
11. 11.🔁 What number does this code show?
    let marks = [23, 83, 37, 95, 10];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 0, 1, 2, 3
13. 13.🔁 What number does this code show?
    let runs = [19, 17, 15, 20, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
14. 14.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Aman (c) Hi, Meera
15. 15.🔁 What number does this code show?
    let steps = [80, 34, 80];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
16. 16.🔁 What number does this code show?
    let scores = [92, 63, 91];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What number does this code show?
    let marks = [84, 39, 48];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
18. 18.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it is slower (d) it uses more lines
19. 19.🔁 What number does this code show?
    let scores = [9, 6, 16, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
20. 20.🔁 What number does this code show?
    let marks = [91, 52, 67, 97];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
21. 21.🔁 What number does this code show?
    let runs = [11, 14, 6, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
22. 22.🔁 What number does this code show?
    let marks = [19, 7, 7, 12, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
23. 23.🔁 What number does this code show?
    let runs = [7, 9, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
24. 24.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Zoya", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Meera
25. 25.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 1 (d) 6
26. 26.🔁 What number does this code show?
    let runs = [20, 4, 18, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
27. 27.🔁 What number does this code show?
    let runs = [8, 19, 20, 17];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Aman", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir (d) Hi, Zoya
29. 29.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman
30. 30.🔁 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, Kabir (b) Hi, Aman (c) Hi, Riya
31. 31.🔁 What number does this code show?
    let scores = [8, 16, 18, 12];
    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 = ["Meera", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Arjun (c) Hi, Riya
33. 33.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Aman", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Aman (d) Hi, Riya
34. 34.🔁 What number does this code show?
    let marks = [16, 12, 15, 10, 13];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
35. 35.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Riya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Kabir
36. 36.🔁 What number does this code show?
    let steps = [25, 36, 26, 94, 33];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let marks = [2, 20, 5, 3, 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 scores = [4, 7, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
39. 39.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
40. 40.🔁 What number does this code show?
    let runs = [73, 72, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);

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