App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 229 · 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 = [10, 10, 5, 1, 19];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
2. 2.🔁 What number does this code show?
   let runs = [26, 82, 60, 18, 11];
   let count = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
3. 3.🔁 What is the LAST line this code shows?
   let names = ["Arjun", "Riya", "Zoya"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya
4. 4.🔁 What number does this code show?
   let steps = [1, 13, 1, 20];
   let total = 0;
   for (let i = 0; i < steps.length; i++) {
     total = total + steps[i];
   }
   show(total);
5. 5.🔁 What number does this code show?
   let runs = [3, 16, 1];
   let total = 0;
   for (let i = 0; i < runs.length; i++) {
     total = total + runs[i];
   }
   show(total);
6. 6.🔁 What number does this code show?
   let scores = [8, 19, 17, 18];
   let total = 0;
   for (let i = 0; i < scores.length; i++) {
     total = total + scores[i];
   }
   show(total);
7. 7.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 1 (d) 6
8. 8.🔁 What number does this code show?
   let steps = [20, 63, 21];
   let count = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] >= 70) {
       count = count + 1;
     }
   }
   show(count);
9. 9.🔁 What number does this code show?
   let scores = [19, 4, 5];
   let best = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] > best) {
       best = scores[i];
     }
   }
   show(best);
10. 10.🔁 What number does this code show?
    let steps = [13, 16, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
11. 11.🔁 What number does this code show?
    let scores = [55, 86, 75, 33, 56];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
12. 12.🔁 What number does this code show?
    let scores = [6, 7, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
13. 13.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Meera
14. 14.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) less code to write (d) it is slower
15. 15.🔁 What number does this code show?
    let runs = [9, 3, 8];
    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 = [5, 10, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
17. 17.🔁 What number does this code show?
    let runs = [8, 14, 3, 1];
    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 steps = [5, 10, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
19. 19.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 3 (d) 0, 1, 2
20. 20.🔁 What number does this code show?
    let marks = [81, 63, 42];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
21. 21.🔁 What number does this code show?
    let steps = [17, 1, 3, 4];
    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 scores = [13, 10, 19];
    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 marks = [59, 52, 66, 48, 34];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let runs = [42, 99, 37];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let scores = [3, 18, 20, 7, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
26. 26.🔁 What number does this code show?
    let runs = [18, 17, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
27. 27.🔁 list.length tells you ___. (a) the first item (b) the last item (c) the biggest item (d) how many items it has
28. 28.🔁 What number does this code show?
    let steps = [19, 18, 13, 15, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
29. 29.🔁 What number does this code show?
    let steps = [20, 16, 1, 19];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
30. 30.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Aman (b) Hi, Meera (c) Hi, Arjun (d) Hi, Riya
31. 31.🔁 What number does this code show?
    let steps = [12, 6, 7];
    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 runs = [4, 3, 1];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
33. 33.🔁 What number does this code show?
    let marks = [70, 68, 81];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What number does this code show?
    let runs = [21, 15, 50];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
35. 35.🔁 What number does this code show?
    let steps = [33, 57, 78, 38, 36];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
36. 36.🔁 What number does this code show?
    let steps = [7, 17, 16, 13, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
37. 37.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Meera
38. 38.🔁 What number does this code show?
    let scores = [1, 10, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
39. 39.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Aman
40. 40.🔁 What number does this code show?
    let scores = [88, 20, 12, 73, 38];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);

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