App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 325 · 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 = [3, 8, 12, 5];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
2. 2.🔁 What number does this code show?
   let scores = [4, 16, 15];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
3. 3.🔁 What number does this code show?
   let steps = [19, 20, 8, 9];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
4. 4.🔁 What number does this code show?
   let scores = [9, 8, 6, 2, 5];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
5. 5.🔁 What number does this code show?
   let scores = [68, 36, 34, 73, 33];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
6. 6.🔁 What number does this code show?
   let runs = [15, 9, 10, 15];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
7. 7.🔁 What does a loop do? (a) repeats code (b) draws icons (c) saves photos (d) deletes code
8. 8.🔁 What number does this code show?
   let runs = [20, 16, 16];
   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 = ["Riya", "Arjun", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Arjun (b) Hi, Aman (c) Hi, Riya
10. 10.🔁 What number does this code show?
    let runs = [93, 23, 48, 43];
    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 = ["Kabir", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Kabir
12. 12.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
13. 13.🔁 What number does this code show?
    let steps = [2, 20, 6, 7, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
14. 14.🔁 What number does this code show?
    let scores = [1, 3, 14, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
15. 15.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Kabir
16. 16.🔁 What number does this code show?
    let scores = [13, 71, 33, 74];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Aman
18. 18.🔁 What number does this code show?
    let scores = [1, 13, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman
20. 20.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Meera (d) Hi, Arjun
21. 21.🔁 What number does this code show?
    let marks = [4, 1, 11, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
22. 22.🔁 What number does this code show?
    let scores = [3, 9, 11];
    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 = [9, 5, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
24. 24.🔁 What number does this code show?
    let marks = [55, 10, 47, 23, 18];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let steps = [29, 55, 19, 42];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
26. 26.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Arjun
27. 27.🔁 What number does this code show?
    let runs = [7, 15, 1, 3, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
28. 28.🔁 What number does this code show?
    let runs = [92, 68, 90, 54, 42];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
29. 29.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2, 3 (d) 0, 1, 2
30. 30.🔁 What number does this code show?
    let runs = [18, 14, 10, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
31. 31.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 6 (d) 1
32. 32.🔁 What number does this code show?
    let scores = [26, 53, 46, 80];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
33. 33.🔁 What number does this code show?
    let marks = [2, 19, 20];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
34. 34.🔁 What number does this code show?
    let steps = [1, 7, 6, 3];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
35. 35.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Meera
36. 36.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Meera (c) Hi, Riya (d) Hi, Arjun
37. 37.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) less code to write (d) it hides them
38. 38.🔁 What number does this code show?
    let runs = [3, 4, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
39. 39.🔁 What number does this code show?
    let scores = [38, 35, 84, 37];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
40. 40.🔁 What number does this code show?
    let runs = [8, 9, 18, 8, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

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