App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 40 · 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 scores = [11, 16, 6];
   let best = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] > best) {
       best = scores[i];
     }
   }
   show(best);
2. 2.🔁 What number does this code show?
   let steps = [4, 13, 1];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
3. 3.🔁 What number does this code show?
   let steps = [4, 7, 18];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
4. 4.🔁 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
5. 5.🔁 What number does this code show?
   let steps = [8, 13, 15, 18, 6];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
6. 6.🔁 What number does this code show?
   let steps = [11, 16, 12];
   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 steps = [7, 2, 13, 12];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
8. 8.🔁 What number does this code show?
   let steps = [16, 70, 22, 94];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
9. 9.🔁 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
10. 10.🔁 What does a loop do? (a) repeats code (b) deletes code (c) draws icons (d) saves photos
11. 11.🔁 What number does this code show?
    let runs = [3, 7, 12, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya
13. 13.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Meera", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Aman
14. 14.🔁 What number does this code show?
    let steps = [2, 16, 2, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
15. 15.🔁 What number does this code show?
    let scores = [4, 18, 2, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
16. 16.🔁 What number does this code show?
    let steps = [9, 17, 3, 10, 17];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
17. 17.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the first item (d) the last item
18. 18.🔁 What number does this code show?
    let marks = [10, 9, 16, 19];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
19. 19.🔁 What number does this code show?
    let steps = [18, 6, 17, 10];
    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 marks = [19, 6, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
21. 21.🔁 What number does this code show?
    let marks = [10, 17, 9, 2, 18];
    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 steps = [11, 14, 12, 7, 19];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
23. 23.🔁 What number does this code show?
    let scores = [94, 67, 18];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let steps = [18, 3, 4, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
25. 25.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Aman", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Riya
26. 26.🔁 What number does this code show?
    let steps = [12, 79, 64];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
27. 27.🔁 What number does this code show?
    let steps = [14, 18, 17, 9, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
28. 28.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Arjun", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Arjun
29. 29.🔁 What number does this code show?
    let scores = [19, 45, 71, 32];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
30. 30.🔁 What number does this code show?
    let steps = [5, 2, 18];
    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 = [11, 12, 7, 17, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
32. 32.🔁 What number does this code show?
    let marks = [20, 6, 12, 3, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
33. 33.🔁 What number does this code show?
    let scores = [61, 16, 79, 41];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Meera
35. 35.🔁 What number does this code show?
    let scores = [3, 1, 9, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
36. 36.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Kabir", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Zoya
37. 37.🔁 What number does this code show?
    let runs = [17, 16, 2, 9];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
38. 38.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Meera (c) Hi, Zoya (d) Hi, Aman
39. 39.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 5 (d) 4
40. 40.🔁 What number does this code show?
    let runs = [12, 11, 4, 15, 1];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);

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