App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 718 · 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 = [50, 93, 73];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 50) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What number does this code show?
   let marks = [94, 25, 95, 14, 85];
   let count = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 list.length tells you ___. (a) the first item (b) the last item (c) how many items it has (d) the biggest item
4. 4.🔁 What number does this code show?
   let marks = [4, 3, 14, 6];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
5. 5.🔁 What number does this code show?
   let scores = [15, 2, 9];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
6. 6.🔁 What number does this code show?
   let marks = [10, 20, 15, 4, 16];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
7. 7.🔁 What is the LAST line this code shows?
   let names = ["Kabir", "Meera", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Aman
8. 8.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 1 (c) 4 (d) 6
9. 9.🔁 What is the LAST line this code shows?
   let names = ["Riya", "Kabir", "Aman", "Meera"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Aman
10. 10.🔁 What number does this code show?
    let runs = [4, 12, 20, 3];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
11. 11.🔁 What number does this code show?
    let steps = [67, 94, 25, 24, 18];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 What number does this code show?
    let marks = [65, 23, 17, 24, 26];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
13. 13.🔁 What number does this code show?
    let steps = [19, 10, 9, 9];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
14. 14.🔁 What number does this code show?
    let marks = [18, 39, 76, 78, 73];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let runs = [14, 5, 4, 7, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
16. 16.🔁 What number does this code show?
    let marks = [29, 98, 78];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What number does this code show?
    let steps = [25, 61, 10, 43, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
18. 18.🔁 What number does this code show?
    let steps = [54, 82, 56, 15];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
19. 19.🔁 What number does this code show?
    let steps = [1, 9, 16];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
20. 20.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2 (b) 3 (c) 1, 2, 3 (d) 0, 1, 2, 3
21. 21.🔁 What number does this code show?
    let scores = [20, 2, 13, 15];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
22. 22.🔁 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
23. 23.🔁 What number does this code show?
    let scores = [45, 13, 43, 43, 79];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya (d) Hi, Arjun
25. 25.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Zoya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
26. 26.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Riya", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Aman (c) Hi, Meera (d) Hi, Arjun
27. 27.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Kabir
28. 28.🔁 What does a loop do? (a) saves photos (b) draws icons (c) repeats code (d) deletes code
29. 29.🔁 What number does this code show?
    let runs = [37, 33, 60];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
30. 30.🔁 What number does this code show?
    let steps = [12, 19, 7];
    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 steps = [36, 57, 69, 57, 17];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
32. 32.🔁 What number does this code show?
    let scores = [14, 6, 4, 9, 2];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
33. 33.🔁 What number does this code show?
    let runs = [6, 8, 17, 16];
    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 runs = [4, 4, 17, 19, 2];
    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 runs = [70, 59, 99];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let marks = [21, 97, 83];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let runs = [20, 20, 18, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
38. 38.🔁 What number does this code show?
    let scores = [69, 92, 58, 26];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
39. 39.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Meera", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Aman (d) Hi, Riya
40. 40.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya

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