App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 83 · 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.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) it hides them (d) less code to write
2. 2.🔁 What number does this code show?
   let steps = [74, 69, 71];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What number does this code show?
   let steps = [78, 83, 37, 89, 29];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
4. 4.🔁 What number does this code show?
   let steps = [32, 57, 52, 31, 91];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What number does this code show?
   let scores = [70, 17, 75, 35, 80];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 50) {
       count = count + 1;
     }
   }
   show(count);
6. 6.🔁 What number does this code show?
   let runs = [16, 13, 8, 2, 3];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
7. 7.🔁 What number does this code show?
   let scores = [68, 12, 19, 13];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 50) {
       count = count + 1;
     }
   }
   show(count);
8. 8.🔁 What number does this code show?
   let steps = [5, 3, 1];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
9. 9.🔁 What number does this code show?
   let steps = [8, 11, 6, 2];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
10. 10.🔁 What does a loop do? (a) deletes code (b) saves photos (c) repeats code (d) draws icons
11. 11.🔁 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
12. 12.🔁 What number does this code show?
    let marks = [17, 72, 78, 43, 20];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
13. 13.🔁 What number does this code show?
    let runs = [12, 18, 20, 12, 9];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
14. 14.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 5 (c) 4 (d) 1
15. 15.🔁 What number does this code show?
    let scores = [9, 6, 7, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
16. 16.🔁 What number does this code show?
    let steps = [18, 8, 1, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
17. 17.🔁 What number does this code show?
    let runs = [10, 13, 3, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
18. 18.🔁 What number does this code show?
    let scores = [15, 18, 14, 17, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
19. 19.🔁 What number does this code show?
    let runs = [9, 1, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
20. 20.🔁 What number does this code show?
    let marks = [10, 7, 4, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
21. 21.🔁 What number does this code show?
    let steps = [3, 6, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
22. 22.🔁 What number does this code show?
    let steps = [9, 4, 3, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
23. 23.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Meera (c) Hi, Aman (d) Hi, Riya
24. 24.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Arjun
25. 25.🔁 What number does this code show?
    let runs = [2, 12, 9, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
26. 26.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Riya (c) Hi, Meera (d) Hi, Zoya
27. 27.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Aman (d) Hi, Riya
28. 28.🔁 What number does this code show?
    let scores = [59, 41, 75, 39];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
29. 29.🔁 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, Riya (c) Hi, Aman
30. 30.🔁 What number does this code show?
    let scores = [11, 19, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
31. 31.🔁 What number does this code show?
    let marks = [5, 2, 4, 3, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
32. 32.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Meera (c) Hi, Zoya
33. 33.🔁 What number does this code show?
    let runs = [12, 84, 59, 16, 54];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 list.length tells you ___. (a) the first item (b) the biggest item (c) the last item (d) how many items it has
35. 35.🔁 What number does this code show?
    let scores = [13, 3, 16, 16];
    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 = [5, 18, 9, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
37. 37.🔁 What number does this code show?
    let scores = [7, 14, 1, 10, 11];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
38. 38.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Arjun", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Meera
39. 39.🔁 What number does this code show?
    let scores = [1, 11, 13, 5, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
40. 40.🔁 What number does this code show?
    let scores = [12, 7, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

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