App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 660 · 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 runs = [86, 96, 68, 59];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What number does this code show?
   let steps = [38, 14, 61];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What does a loop do? (a) saves photos (b) repeats code (c) draws icons (d) deletes code
4. 4.🔁 What number does this code show?
   let runs = [13, 6, 6];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
5. 5.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
6. 6.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 3 (c) 0, 1, 2, 3 (d) 0, 1, 2
7. 7.🔁 What is the LAST line this code shows?
   let names = ["Meera", "Kabir", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Aman (b) Hi, Meera (c) Hi, Kabir
8. 8.🔁 What is the LAST line this code shows?
   let names = ["Meera", "Kabir", "Riya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera
9. 9.🔁 What number does this code show?
   let runs = [1, 17, 13, 14, 15];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
10. 10.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 5 (c) 4 (d) 1
11. 11.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Riya
12. 12.🔁 What number does this code show?
    let runs = [12, 5, 1, 10, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
13. 13.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Arjun
14. 14.🔁 What number does this code show?
    let scores = [7, 6, 5, 14];
    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 steps = [15, 1, 16, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
16. 16.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
17. 17.🔁 What number does this code show?
    let steps = [7, 12, 14, 8, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
18. 18.🔁 What number does this code show?
    let runs = [49, 24, 78];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
19. 19.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it is slower (d) it uses more lines
20. 20.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir
21. 21.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Zoya
22. 22.🔁 What number does this code show?
    let steps = [5, 16, 14, 19, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
23. 23.🔁 What number does this code show?
    let runs = [19, 11, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
24. 24.🔁 What number does this code show?
    let scores = [52, 12, 99];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let steps = [24, 53, 42];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
26. 26.🔁 What number does this code show?
    let scores = [68, 71, 80];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 What number does this code show?
    let steps = [1, 17, 15];
    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 = ["Riya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera
29. 29.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Meera (d) Hi, Riya
30. 30.🔁 What number does this code show?
    let marks = [14, 44, 21];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
31. 31.🔁 What number does this code show?
    let marks = [4, 16, 4, 11];
    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 steps = [17, 10, 17, 6, 4];
    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 marks = [18, 16, 11, 15, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
34. 34.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Zoya
35. 35.🔁 What number does this code show?
    let runs = [2, 5, 13, 10, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
36. 36.🔁 What number does this code show?
    let scores = [98, 10, 30];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let steps = [18, 16, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
38. 38.🔁 What number does this code show?
    let scores = [15, 9, 20, 4];
    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 scores = [16, 7, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
40. 40.🔁 What number does this code show?
    let scores = [34, 32, 88, 23];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);

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