CodeHS Functions and Control Variables

Why do we write functions?

• Make our code easier to understand by giving a readable name to a group of instructions

• Avoid writing repeated code

• Make our code reusable

• All of the above

In the following function printThreeTimes:

function printThreeTimes(word){

println(word);

println(word);

println(word);

}

What is the parameter of the function?

• printThreeTimes

• function

• println

• word

What is the output of the following program?

function start(){

var x = 5;

sumTo(x);

println(x);

}

function sumTo(num){

var sum = 0;

for(var i = 0; i <= num; i++){

sum += i;

}

println(sum);

}

• 5

  15

• 15

  5

• 5

• 15

• none, there is a syntax error

What is printed by the following program?

function printNumbers(two, one, zero){

println(two);

println(one);

println(zero);

}

function start(){

var zero = 0;

var one = 1;

var two = 2;

printNumbers(zero, one, two);

}

• 2

  1

  0

• 0

  1

  2

• zero

  one

  two

• two

  one

  zero

How many parameters go into the function sum, and how many return values come out of the function sum?

function sum(first, second, third){

var result = first + second + third;

println(first);

println(second);

println(third);

return result;

}

• 3 parameters go in, 1 return value comes out

• 3 parameters go in, 3 return values come out

• 1 parameter goes in, 4 return values come out

• 1 parameter goes in, 1 return value comes out

“It’s a bird! It’s a plane! No, it’s Superman!”

We want to write a function isSuperman that takes in two parameters isBird and isPlane and returns true if it is in fact Superman, and false otherwise.

If it’s not a bird and it’s not a plane, it must be Superman.

Which of the following functions is the correct implementation of isSuperman?

• function isSuperman(isBird, isPlane){

  return isBird || isPlane;

  }

• function isSuperman(isBird, isPlane){

  return !isBird || !isPlane;

  }

• function isSuperman(isBird, isPlane){

  return !isBird && !isPlane;

  }

• function isSuperman(isBird, isPlane){

  return isBird && isPlane;

  }

In the following code:

function start(){

var length = 5;

var width = 4;

rectangleArea(length, width);

}

// This function prints out the area of

// a triangle given its base and height

function rectangleArea(base, height){

var area = base * height;

println(area);

}

What are the names of the parameters?

• length and width

• length and height

• base and height

• base and width

What is printed by the following program?

function product(x, y){

return x * y;

}

function difference(x, y){

return x - y;

}

function start(){

var x = 2;

var y = 5;

var value1 = product(x, y);

var value2 = difference(y, x);

var result = difference(value1, value2);

println(result);

}

• 7

• -7

• 13

• -13

In the following code:

function drawCircle(radius, x, y, color) {

var circle = new Circle(radius);

circle.setPosition(x, y);

circle.setColor(color);

add(circle);

}

What is the minimum number of parameters that must be given when calling the ‘drawCircle’ function?

• Four

• Three

• Two

• One

What will be printed to the screen when the following program is run?

function start(){

println(doubleNumber(doubleNumber(10)));

}

function doubleNumber(x){

var doubledX = 2 * x;

return doubledX;

}

• 10

• 20

• 40

• 100