App Dev Worksheet: Functions

App development lesson 20: Functions · Set 187 · 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(5));
2. 2.🧰 What number does this code show?
   function total(price, qty) {
     return price * qty;
   }
   show(total(10, 2));
3. 3.🧰 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(2) + fee(8));
4. 4.🧰 What number does this code show?
   function total(price, qty) {
     return price * qty;
   }
   show(total(50, 2));
5. 5.🧰 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(7) + fee(11));
6. 6.🧰 Why write a function? (a) to hide errors (b) to reuse code (c) to make code longer (d) to slow the app
7. 7.🧰 What number does this code show?
   function points(stars) {
     return stars * 10 + 5;
   }
   show(points(5) + points(5));
8. 8.🧰 What number does this code show?
   function points(stars) {
     return stars * 10 + 5;
   }
   show(points(2) + points(4));
9. 9.🧰 What number does this code show?
   function points(stars) {
     return stars * 10 + 5;
   }
   show(points(5) + points(3));
10. 10.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(5) + points(0));
11. 11.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(3) + points(0));
12. 12.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(80, 2));
13. 13.🧰 What number does this code show?
    function triple(n) {
      return n * 3;
    }
    show(triple(5));
14. 14.🧰 What does this code show?
    function greet(name) {
      return "Hello, " + name + "!";
    }
    show(greet("Aman")); (a) Hello, Aman! (b) Hello, name! (c) greet (d) Aman
15. 15.🧰 What does return do in a function? (a) sends back a value (b) deletes the app (c) repeats the code (d) closes the screen
16. 16.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(1) + points(0));
17. 17.🧰 What number does this code show?
    function triple(n) {
      return n * 3;
    }
    show(triple(11));
18. 18.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(60, 2));
19. 19.🧰 What number does this code show?
    function double(n) {
      return n * 2;
    }
    show(double(7));
20. 20.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(70, 3));
21. 21.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(85, 5));
22. 22.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(50, 4));
23. 23.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(40, 5));
24. 24.🧰 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(3) + fee(4));
25. 25.🧰 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(2) + fee(7));
26. 26.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(5) + points(2));
27. 27.🧰 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(12));
28. 28.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(65, 5));
29. 29.🧰 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(8) + fee(3));
30. 30.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(1) + points(4));
31. 31.🧰 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(2) + fee(11));
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 20;
    }
    show(fee(8) + fee(11));
33. 33.🧰 What number does this code show?
    function double(n) {
      return n * 2;
    }
    show(double(25));
34. 34.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(2) + points(2));
35. 35.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(1) + points(1));
36. 36.🧰 What number does this code show?
    function total(price, qty) {
      return price * qty;
    }
    show(total(95, 2));
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 60;
    }
    show(fee(7) + fee(7));
38. 38.🧰 What number does this code show?
    function triple(n) {
      return n * 3;
    }
    show(triple(17));
39. 39.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(4) + points(0));
40. 40.🧰 What number does this code show?
    function points(stars) {
      return stars * 10 + 5;
    }
    show(points(4) + points(2));

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