App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 26 · 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.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 4 (d) 5
2. 2.🔁 What number does this code show?
   let runs = [7, 4, 8, 7, 13];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
3. 3.🔁 What is the LAST line this code shows?
   let names = ["Zoya", "Aman", "Kabir"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman
4. 4.🔁 What number does this code show?
   let steps = [63, 74, 50];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What number does this code show?
   let steps = [40, 25, 70, 42, 34];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
6. 6.🔁 What number does this code show?
   let marks = [24, 60, 34];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
7. 7.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) how many items it has (d) the first item
8. 8.🔁 What number does this code show?
   let runs = [7, 1, 6];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
9. 9.🔁 What is the LAST line this code shows?
   let names = ["Meera", "Riya", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman
10. 10.🔁 What number does this code show?
    let runs = [18, 2, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
11. 11.🔁 What number does this code show?
    let marks = [81, 80, 54];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 What number does this code show?
    let marks = [14, 16, 13, 10, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
13. 13.🔁 What number does this code show?
    let runs = [20, 19, 17, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
14. 14.🔁 What number does this code show?
    let steps = [86, 85, 28, 86, 56];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let runs = [93, 14, 43, 58];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
16. 16.🔁 What does a loop do? (a) saves photos (b) deletes code (c) repeats code (d) draws icons
17. 17.🔁 What number does this code show?
    let scores = [19, 5, 7, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
18. 18.🔁 What number does this code show?
    let steps = [17, 7, 1, 13, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
19. 19.🔁 What number does this code show?
    let runs = [53, 98, 96, 87, 78];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
20. 20.🔁 What number does this code show?
    let runs = [9, 20, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
21. 21.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Riya (d) Hi, Kabir
22. 22.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2 (b) 3 (c) 0, 1, 2, 3 (d) 1, 2, 3
23. 23.🔁 What number does this code show?
    let marks = [51, 89, 40, 81];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let marks = [90, 19, 80, 49, 36];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let marks = [9, 8, 15, 13, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
26. 26.🔁 What number does this code show?
    let runs = [16, 12, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
27. 27.🔁 What number does this code show?
    let steps = [33, 47, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
28. 28.🔁 What number does this code show?
    let steps = [4, 12, 5, 4];
    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 = ["Zoya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Aman
30. 30.🔁 What number does this code show?
    let steps = [16, 2, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
31. 31.🔁 What number does this code show?
    let runs = [1, 19, 5, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
32. 32.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) less code to write (d) it is slower
33. 33.🔁 What number does this code show?
    let runs = [5, 7, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
34. 34.🔁 What number does this code show?
    let marks = [8, 13, 2, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
35. 35.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Aman (d) Hi, Zoya
36. 36.🔁 What number does this code show?
    let marks = [16, 1, 4, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
37. 37.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Riya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
38. 38.🔁 What number does this code show?
    let marks = [77, 33, 37];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
39. 39.🔁 What number does this code show?
    let steps = [19, 7, 5, 16];
    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 marks = [16, 13, 7, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);

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