App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 795 · 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 = [16, 15, 15];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
2. 2.🔁 What number does this code show?
   let runs = [1, 7, 18, 8];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
3. 3.🔁 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
4. 4.🔁 list.length tells you ___. (a) the first item (b) the last item (c) the biggest item (d) how many items it has
5. 5.🔁 What number does this code show?
   let runs = [29, 52, 78, 86];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
6. 6.🔁 What number does this code show?
   let steps = [6, 8, 16, 14];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
7. 7.🔁 What number does this code show?
   let runs = [15, 14, 12, 4];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
8. 8.🔁 What number does this code show?
   let scores = [8, 5, 4];
   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 scores = [39, 21, 41, 38];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 60) {
       count = count + 1;
     }
   }
   show(count);
10. 10.🔁 What number does this code show?
    let runs = [14, 57, 34, 35, 48];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
11. 11.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Riya (d) Hi, Aman
12. 12.🔁 What number does this code show?
    let steps = [79, 58, 33];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
13. 13.🔁 What number does this code show?
    let marks = [16, 12, 40];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
14. 14.🔁 What number does this code show?
    let marks = [31, 99, 72, 31];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let steps = [63, 97, 27, 81];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
16. 16.🔁 What does a loop do? (a) saves photos (b) draws icons (c) repeats code (d) deletes code
17. 17.🔁 What number does this code show?
    let steps = [11, 15, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
18. 18.🔁 What number does this code show?
    let steps = [10, 20, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
19. 19.🔁 What number does this code show?
    let steps = [14, 20, 10, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
20. 20.🔁 What number does this code show?
    let scores = [2, 20, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
21. 21.🔁 What number does this code show?
    let steps = [19, 2, 14, 14];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
22. 22.🔁 What number does this code show?
    let scores = [1, 5, 15, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
23. 23.🔁 What number does this code show?
    let scores = [18, 12, 12, 14, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
24. 24.🔁 Why use a loop to show 100 messages? (a) it is slower (b) less code to write (c) it uses more lines (d) it hides them
25. 25.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 1 (c) 6 (d) 5
26. 26.🔁 What number does this code show?
    let marks = [80, 68, 86, 37];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 What number does this code show?
    let scores = [2, 2, 15, 3, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
28. 28.🔁 What number does this code show?
    let scores = [8, 1, 10, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
29. 29.🔁 What number does this code show?
    let marks = [19, 3, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
30. 30.🔁 What number does this code show?
    let scores = [19, 5, 17, 2, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
31. 31.🔁 What number does this code show?
    let runs = [95, 18, 46, 82, 33];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
32. 32.🔁 What number does this code show?
    let steps = [88, 72, 79, 44, 72];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
33. 33.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir
34. 34.🔁 What number does this code show?
    let runs = [15, 17, 16];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
35. 35.🔁 What number does this code show?
    let scores = [14, 11, 20, 15, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
36. 36.🔁 What number does this code show?
    let steps = [84, 95, 59, 39, 53];
    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 = [96, 19, 40, 12, 98];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
38. 38.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Riya (d) Hi, Arjun
39. 39.🔁 What number does this code show?
    let steps = [6, 2, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
40. 40.🔁 What number does this code show?
    let steps = [4, 15, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);

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