App Dev Worksheet: Functions

App development lesson 20: Functions · Set 430 · 40 questions

Developer's tip (Write once, use often): function name(parameter) { …; return result; } — call it with name(value). Work out each call separately, then finish the line. Inside a function, if / return can give different results for different inputs.

1. 1.🧰 What number does this code show?
   function double(n) {
     return n * 2;
   }
   show(double(3));
2. 2.🧰 What number does this code show?
   function triple(n) {
     return n * 3;
   }
   show(triple(5));
3. 3.🧰 What number does this code show?
   function total(price, qty) {
     return price * qty;
   }
   show(total(75, 5));
4. 4.🧰 In function tip(bill), what is bill? (a) a parameter (b) a screen (c) a loop (d) an event
5. 5.🧰 Why write a function? (a) to reuse code (b) to hide errors (c) to make code longer (d) to slow the app
6. 6.🧰 What number does this code show?
   function total(price, qty) {
     return price * qty;
   }
   show(total(30, 6));
7. 7.🧰 What does return do in a function? (a) deletes the app (b) closes the screen (c) repeats the code (d) sends back a value
8. 8.🧰 What does this code show?
   function greet(name) {
     return "Hello, " + name + "!";
   }
   show(greet("Meera")); (a) Hello, Meera! (b) Hello, name! (c) greet (d) Meera
9. 9.🧰 What number does this code show?
   function points(stars) {
     return stars * 10 + 5;
   }
   show(points(4) + points(1));
10. 10.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 40;
    }
    show(fee(1) + fee(6));
11. 11.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(4) + points(2));
12. 12.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(4) + points(5));
13. 13.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(5) + points(2));
14. 14.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 20;
    }
    show(fee(10) + fee(5));
15. 15.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(5) + points(5));
16. 16.🧰 What is a function? (a) a screen size (b) a list of colours (c) a named block of code (d) a type of phone
17. 17.🧰 What number does this code show?
    function double(n) {
      return n * 2;
    }
    show(double(5));
18. 18.🧰 What number does this code show?
    function triple(n) {
      return n * 3;
    }
    show(triple(40));
19. 19.🧰 What does this code show?
    function greet(name) {
      return "Hi, " + name + "!";
    }
    show(greet("Arjun")); (a) Arjun (b) Hi, name! (c) Hi, Arjun! (d) greet
20. 20.🧰 What number does this code show?
    function double(n) {
      return n * 2;
    }
    show(double(37));
21. 21.🧰 What number does this code show?
    function double(n) {
      return n * 2;
    }
    show(double(38));
22. 22.🧰 What does this code show?
    function greet(name) {
      return "Hello, " + name + "!";
    }
    show(greet("Riya")); (a) Hello, Riya! (b) Hello, name! (c) greet (d) Riya
23. 23.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(30, 3));
24. 24.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(40, 6));
25. 25.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(100, 6));
26. 26.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(3) + points(1));
27. 27.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(80, 5));
28. 28.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 50;
    }
    show(fee(10) + fee(6));
29. 29.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(100, 5));
30. 30.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(1) + points(5));
31. 31.🧰 What does this code show?
    function greet(name) {
      return "Welcome, " + name + "!";
    }
    show(greet("Kabir")); (a) greet (b) Welcome, Kabir! (c) Kabir (d) Welcome, name!
32. 32.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 60;
    }
    show(fee(1) + fee(6));
33. 33.🧰 What number does this code show?
    function triple(n) {
      return n * 3;
    }
    show(triple(29));
34. 34.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(50, 3));
35. 35.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(100, 4));
36. 36.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 50;
    }
    show(fee(9) + fee(11));
37. 37.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 20;
    }
    show(fee(10) + fee(1));
38. 38.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(100, 3));
39. 39.🧰 A museum app works out the entry fee. What number does this code show?
    function fee(age) {
      if (age < 5) {
        return 0;
      }
      return 30;
    }
    show(fee(1) + fee(1));
40. 40.🧰 What number does this code show?
    function triple(n) {
      return n * 3;
    }
    show(triple(25));

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