App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 397 · 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 does a loop do? (a) repeats code (b) deletes code (c) saves photos (d) draws icons
2. 2.🔁 What number does this code show?
   let steps = [7, 8, 19, 19, 12];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
3. 3.🔁 What number does this code show?
   let marks = [6, 6, 3, 4, 13];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
4. 4.🔁 What number does this code show?
   let scores = [13, 83, 76];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What is the LAST line this code shows?
   let names = ["Meera", "Zoya", "Arjun"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Meera
6. 6.🔁 What is the LAST line this code shows?
   let names = ["Meera", "Aman", "Riya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman
7. 7.🔁 What number does this code show?
   let scores = [15, 9, 19, 13, 3];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
8. 8.🔁 What number does this code show?
   let runs = [2, 14, 14];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
9. 9.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 1 (c) 5 (d) 6
10. 10.🔁 What number does this code show?
    let marks = [7, 5, 4, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
11. 11.🔁 What number does this code show?
    let steps = [11, 12, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
12. 12.🔁 What number does this code show?
    let runs = [9, 20, 17, 9, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
13. 13.🔁 What number does this code show?
    let scores = [19, 2, 11, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
14. 14.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
15. 15.🔁 What number does this code show?
    let marks = [19, 15, 1, 15];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
16. 16.🔁 What number does this code show?
    let runs = [41, 93, 54, 25, 62];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
17. 17.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Kabir
18. 18.🔁 What number does this code show?
    let scores = [3, 17, 11, 11, 9];
    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 = ["Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Aman (c) Hi, Arjun
20. 20.🔁 What number does this code show?
    let steps = [15, 7, 3, 15, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
21. 21.🔁 list.length tells you ___. (a) the biggest item (b) the first item (c) the last item (d) how many items it has
22. 22.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Arjun", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Meera (c) Hi, Kabir (d) Hi, Arjun
23. 23.🔁 What number does this code show?
    let steps = [14, 2, 7, 10, 9];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
24. 24.🔁 What number does this code show?
    let scores = [7, 9, 12, 11, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
25. 25.🔁 What number does this code show?
    let scores = [12, 12, 1, 4, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
26. 26.🔁 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
27. 27.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Meera (c) Hi, Arjun
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
29. 29.🔁 What number does this code show?
    let runs = [17, 4, 2, 17, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
30. 30.🔁 What number does this code show?
    let marks = [15, 9, 3, 14, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
31. 31.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 3 (c) 0, 1, 2 (d) 1, 2, 3
32. 32.🔁 What number does this code show?
    let steps = [12, 9, 4, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
33. 33.🔁 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, Meera (c) Hi, Riya
34. 34.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Meera (c) Hi, Aman
35. 35.🔁 What number does this code show?
    let marks = [11, 14, 18, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
36. 36.🔁 What number does this code show?
    let runs = [98, 52, 28, 19];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
37. 37.🔁 What number does this code show?
    let runs = [13, 9, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
38. 38.🔁 What number does this code show?
    let scores = [4, 10, 1];
    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 = [56, 51, 46, 96];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
40. 40.🔁 What number does this code show?
    let scores = [2, 7, 13, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

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